Hoping someone could impart some knowledge my way, Seemingly overnight last week my car developed a really rough idle not just on cold startup but whenever i come to a stop or clutch in, so much so that at time the idle will drop so far that it'll stall. Now i have a rubbish Bluetooth OBD adapter and the torque app that i used to pull a p0508 code from the ecu (P0508 - Idle control system circuit low input) i took the IACV off and thoroughly cleaned it and replaced the gasket, this did nothing to remedy the idle problem so i actually purchased a new IACV and gasket to try that out (wanted to fix it asap and on my own if possible), this also did not help at all.
now ive read that this can be attributed to a number of things including vac leaks and bad plugs / fuel filters etc, So i thought i would change the plugs and filter and see if this remedied the issue. to my dismay it did not help at all. next i pulled the throttle body off and cleaned it out (was filthy to say the least) also did nothing, and now i am feeling a little lost as to what it might be.
Can anyone shed some light as to what it could be? again the car seems to drive perfectly fine when under acceleration but when idling its very rough and when the Fans kick on it really struggles to keep idling.
Any help would be much appreciated!
oh btw the car is a 2003 wrx wagon