rough idle

[PlayerZ]

my freind has a 92 vr4, ive been helping him fix it. his car is real hard to start, ( have to push pedal) and when it gets stable it idles to 1500 till it warms a little then it drops down and bounces between 500 - 700. i checked the isc and it read 37 ohms so i had him get a new one. the new one dosent look like the old one but has the right readings. so we put it in and the car is still hard to start but it jumps to 2500 rpms and holds for about three mins and then comes down and bounces from 1300 - 2000 quickly so i put the old one back in and checked it again and it reads 30.1 ohms but still bounceing low at idle cheked all the vac lines they are all in the right spots. checked the hoses at the nipples for cracks or breaks and nothing. so im lost. he has a 16g at 17 psi, a manual boost control, boost gauge, a fmic from a srt 4 the piping isnt the best and could be leaking but cant find any, he has a vpc i think it is to eliminate the maf -- the 16g isnt hitting full spool till 3200 is this a problem i thought they spooled at 2800 thanks for the help sorry i forgot to say that he had some ijectors go bad and he put 550cc in and problem went away and came back

 

[BOBS90TURBO]

I had some probs close to yours and it ended up being a combo of things wrong, first thing was the biss o-ring gasket was leaking(even though it was brand new) easy fix, and my little idle position sensor was not adjusted right, when the throttle closes, it has to hit that sensor perfect, I also had a intake manifold gasket leak, but that only made it idle rough(not surge). Good luck.

 

[PlayerZ]

thanks, ill start there.

 

[PlayerZ]

i cleaned the egr valve and checked the emissions and found a bad purge selinoid. it is leaking still from somewhere but not sure yet where. any other ideas as well as the ones above. he wants to go to the shoot out.