I have a 1994 pontiac sunbird with a 2.0. Recently my car blew the head gasket between cylinders 3 and 4. I have since replaced the head gasket, and while the head was off I had it resurfaced and had a valve job done. I put it back together saturday and since I have done the head gasket the car has a very rough idle. At cold start it's not very bad, just a little rough and then as it warms up it gets much worse. Finally after it's been ran about 20 minutes the idle smooths out completely. The engine runs fine at any other speed except idle, any amount of throttle and it will smooth right out. I have checked and rechecked my vacum lines and i'm 99% sure they're on correctly and there are no leaks. My MAP sensor reads properly with the engine running (35-39 kp), again leading me to believe I have no vacum leaks. I checked my IAC, it's at 19 counts when ideling (about 900 rpms) and it seems to be moving properly. My oxygen sensor seemed to not be working properly, and upon inspection it was very corroded. I replaced it but my car still idles rough. I really have no idea what it could be. I was a little unsure of the way I lined up the timing when I put the car back together, but I would think that would make the car run bad no matter what the temp. I really have no idea where to go next, any help would be greatly appreciated.

you may have to bump the idle up a bit b/c of the vavle job. what kinda valve job did they do, higher seal/flow job, thriple angle, or just simply a valve grind

I got a 3 angle valve job, but the machinist said that it shouldn't affect drivability. I also had to have 11 thousanths machined off the head because it was warped. I used a scan tool to bump up my idle by moving the IAC but until it doesn't smooth out until it gets to 1200-1300. I don't think it's idleing too low, it's just not running right at idle. My book didn't have the way the timing should be lined up, so I had a friend who just put together his 2.0 do it. I'm pretty sure that we got it right, but not completely. The car runs great at anything but idle though, and I figure (tell me if i'm wrong) that if I lined the timing up wrong then it would affect the whole RPM range. My car has always ran pretty cool, I'm not sure if that would have something to do with it now that I've got a little higher flow because of the valve job.

no timin would not affect ONLY idle, the only thing i can think of is that it could be the valve job and heck decking. mine has a single angle vavle grind, and the head was decked one hundread thousanths. mine dont idle too bad, but i also have high compression pistons, and it's a 2.4, u said it wnt smooth out till 1200 rpm?

Well, apparently my friend told me how to do the cam timing wrong. my car is a 94 and we timed it for the 88-89 2.0 engine. I know it sounds funny that it's only affected at idle but i'm almost sure that it's my cam timing. I now know the correct way to do it, so I'm gonna try and fix it today.

well i guess try it and see what happens