Well, like the topic says, my idle is bouncing around 1000-1200 rpm when I'm stopped and in gear. It doesn't happen in neutral. I'm also only making about 8 psi boost now. Vac at idle is approx 20 in Hg. Here's a quick rundown of the latest history

Car is stock with a vac job just complete. After the vac job, the car made 10 psi and a nice boost pattern. The vac/solenoid job also got rid of the problem I had with a hard shift making low boost (1-2 psi in higher gear).

I think that I might have pinched a vac line or that something is leaking. More than likely, I have a leak. The thing that gets me is that it only happens in gear, and not in neutral. The car isn't making the right boost, and I'm amazed at how much 2 psi difference can make in the feel of the car. I have the 3k hesitation and a bad 5th synchro too, so it's almost like I'm driving a cavaqueer when I'm trying to merge onto a highway.

Does anyone have experience with an issue like fluctuating idle ONLY in gear? Is it possibly a vac leak that somehow the ecu doesn't care about at idle? could it be related to my low boost? I'm at a loss and wanted to get some expert opinions before I ripped into it again, because visually with the car put together, everything looks fine. Can anyone direct me to a line/fitting to look for that might cause this? Also, I'm sure I forgot something that people will need to help me out, so please.... yell at me and tell me what other info you need.

 

sounds like a vac leak to me or a intake boot not sitting properly one or the other
recheck your work you will find a leak some where

 

yeah I agree that it sounds like a vac leak... The thing that gets me is that is ran strong after the vac job. I'm hoping something just plain worked loose and I can get in and reconnect it and everything will be straight. Racing season is upon us, and I want to get a good baseline on what the car will do bone stock before I start tearing into it too much. Hopefully there's a single vac line that would cause both probs, and someone a little more educated than me can tell me, but other than that, I'm just stabbing in the dark and checking fittings.

 

I have the same problem intermittently but frequently, and spent over $400 to try to make it go away. No vacume leaks present. I'm starting to think it's the PFC.

 

This is a problem if your idle is not adjusted properly. There are two screws, one in front of the throttle body that has a nut on the bottom, and the other is in the lower back of the TB near the firewall.. it requires a phillips screwdriver.

My idle will sit fine on it's own in neutral, but it will bounce if I am in gear. My idle is set for 1200RPM and I do not have the Idle Speed Control hooked up.

I adjusted my idle screw and set my idle for just over 1000 RPM and it stays solid and does not bounce. You might want to try make some idle adjustments and see if that fixes the problem.

As for the boost leak, I couldn't tell you. Best bet would be to get a vac diagram and trace the lines.. that is always fun =)

Good Luck