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Just to add more info that i thought might be interesting, slidingstrokes put this link up in another thread but it didn\'t work so ive fixed the link and it is really worth a read if your going to do an oil change soon, slightly outdated but still very informative. http://www.lnengineering.com/oiltest.pdf

Yeah was pretty sure the o2 sensor readings were wrong. Am seeking a new one as we speak. Never removed TPS, had intercooler off to check for vac leaks etc and sprayed the #%@* out of it with MAF cleaner, same with the IACV (cheap way i know). Voltage readings were in spec for TPS when i checked with Subaru computer. Tell me bout it.... feels like im just pushing the problem arround rather than fixing it, But thanks for all the suggestions, atleast were making progress :

Okay, i thought the knock would just be because the engine is cold, like Marky said could be some piston slap mistakenly taken as knock or something. The o2 sensor is reading a constant 0.3v at 600 deg, so am going to replace that. My cold idle seems to be all over the place at the moment, will go to its normal 1500rpm then drop right down to 300-500rpm until it nearly stalls then come back up again. once warm just idles at a constant 700 ish. Would having an open O2 sensor circuit cause this when cold? Have cleaned IACV and TPS this morning with contact cleaner, thats when cold idle started doing what its doing.

BUMP, anyone? I have noticed that the front o2 sensor stays at 0.3v shouldn\'t that fluctuate?

Okay got it on the Sub Data computer and this is what came out, Fault code 24 (idle control malfunction) And this is the data, See if you can spot something wrong.... At idle: at 2500(ish) Also is it normal for a knock sensor to pick up knock and retard timing when engine is cold? Was at max knock correction (32 deg I think) when first plugged computer in.

Okay thanks, Thought it best to ask, am trying to sort out a diagnostic computer that i can plug in and just monitor some values to see what comes up. Because at the moment, i\'m at a complete loss. :-\

Yeap, checked plug gaps all were good, coil on plugs and are the new type so not so likely to fail. Just found this today: Is a line to the canister from i\'m assuming the fuel tank(disappears under the car) Line coming down is out the bottom the canister, black line on the right looks like it should connect to the one coming down. Could this cause problems?

Did the fuel filter, forgot to add that to the list sorry.

Still no luck, Changed the fuel pump and still runnning like poo... Car now has hesitation all of the time mainly when cruising, bunny hops when cold, is down on power and idle isn\'t the best, hesitation when under load has come about now too. Have checked/replaced Fuel pump, AFM, Knock Sensor, Plugs, Coils, Fuel Filter. AND still no CEL!

Yes i know it did, but its done this before. It went away when i accidentaly left one of the coil packs uplugged aswell (only runninng on three cylinders ??? ) i dont know which brand but is just an aftermarket copy off trademe, seems to be pretty good quality aswell...

No luck guys, new afm installed still doing the exsact same thing. Loss of power stuttering massive hesitation... Fixed cold idle though. Havent done an ecu reset since install but i cant imagine that would cause this. Next logical place to look? Im thinking fuel pump...

It could be fuel but it doesn\'t sound major, i wouldn\'t worry about it. Most subys will do something of the like when cold. Mine definitely do. If its really bothering you just try some basic stuff, Injector cleaner, Clean air filter, Subaru upper engine cleaner, even just an ECU reset might help (bad batch of fuel = ECU compensation ETC.) If its the very beginning of a sensor fault it will most likely get worse and when it does the car will most likely tell you with a CEL

Also when was the fuel filter last changed? Car needs more fuel when cold if the filters a bit clogged can cause a slight surge when accelerating when cold. Any codes? Probably not a big enough problem to throw them but worth a look.

Oh sorry Orange sticker AA271 from memory

AFM p/n? Sorry, dont know what you mean haha ???

Thats what i thought about mine to, when it next starts playing up just pull over and unplug the AFM you\'ll get a CEL but you know instantly if the car runs better with it unplugged there has to be something wrong with it. On another note, went to the dealer today to price up a new AFM $500 retail !!!!!! he said he would do it for me at $400 (because i do a bit of work for them) still a bit high though. Went on trademe and got an aftermarket replacement for $135, Guy has 100% positve feedback and comes with a 6 month warrranty so should be okay hopefully.

Saw this in the car park when i came out of work awhile ago ;D

Was driving along today, car started doing its cut in and out thing, i got frustrated and just unplugged the MAF car ran brilliantly! if you ignored the CEL. Plugged it back in soon after, Less than 3 km. So defs thinking thats the problem! Will fix and report back!

Is there anyway to test the maf with a multimeter? Other than just unplugging it, because its an intermittent problem. Just so i can see if thats the problem before i go and buy a new one.

Okay so its no that causing cutting out but may help idle. Just found this on rexnet... O2 SENSOR FAULTY SYMPTOM: Rough idle usually cold (Closed loop) and jerky (surging)cruising acceleration. WHY: Because the ECU isnt getting a proper reading anymore and the rough idle and surging is because the ecu is inlimp mode and flooding the car with extra fuel to protect it. Surging problems 9 out of 10 times are always fuel related. sometimes faulty 02 sensor does not throw a CEL code. Well not in the begining anyway. That sounds close, anyone experienced this before??

Could be somthing to do with ICV, if this were to stick open would it allow unmetered air into the engine causing a sudden leaning of mixture and loss of power?? But then why would the car try to open it while crusing?? Might be time for a can of subaru upper engine cleaner?

Haven\'t had a chance to check tps yet but I do remember when we plugged the scan-pro in and read the current data I checked it and it definitely went up with throttle. The airflow meter sounds likens more likely suspect to me because it does just feel like the car is running out of gas, I have a mate who has just got a gtb exactly the same so will see if she will let me "borrow" her afm for a little bit. Haha just to double check will put mine on hers and she what she says

Okay, will check that out tomorrow. One thing i forgot to mention when you start it up from cold the idle will drop really low like very close to stall then pick itself back up to 1500rpm, possibly related?? ???

Hi, yes feels like car is cutting out completely, then if you try to power out of it car bunny hops like its cutting in and out. If you floor it it will hold the rpm you were doing relatively steady for 2-3 seconds then take off. Usually arround 2-3k rpm. Seems to be worse when cars cold. Car is 1996 GTB manual 137ks cambelt done at 117ks and is completely factory standard apart from an alarm and turbo timer.

BP or Mobil 98 always, never anything less, Havent tested fuel pump properly but i have checked it and hot wired it up and worked fine... Wouldnt have a clue about the earthing thing.