1994 BG5 miss issue

[spuddling aka IMPRZF]

Hi all, my mate has recently acquired a 94 BG5 station wagon, manual, twin turbo so on and so forth. The car is completely stock engine wise but has a miss between 5500 and 7000 rpm. It boosts about 7psi on primary and up to 12psi on secondary then develops the miss and starts fluctuating boost pressure . Have done the CEL and came up with 22, faulty knock sensor, so replaced that and reset the computer, took it for a drive it did its miss thing but didn't throw any CEL's when we got back and checked. The car has done 260000. Car has had a new AFM and air filter as well. Could it be spark plugs? Have checked for leaks around all hose's and have replaced any that looked dodgy and all seems fine there. There was a screw in a hose that was leading to the right hand guard,as you look at the motor, I assume to the boost controller that we hooked back up, any reason why this would some one would block off a hose leading there? My mate reckons it was the mechanic who he brought it off that put it in there saying it would lower his boost, prolonging engine life, apparently. Any ideas??

[Joker]

sounds normal - my guess is its knocking? what fuel

[neodowd]

Could be the plugs or a faulty coil, my legacy only started missing around 4500-5000rpm and I had faulty plugs.

[spuddling aka IMPRZF]

Car has also started to loss all revs at high throttle, when the clutch is engaged then disengaged revs come back, boost also drops from 10psi to 0. Any more ideas??

[rex-leggy]

have you checked anything ? like plugs and coils ?

as sugested