Random idle problems

[90tsidude]

Ok first, i did not do a boost leak test. im almost sure i have a vac leak and its ###### the TB seals although neither i think would cause this and its intermittent. Ok while the car is cold the fiav keeps the idle up and it idles just fine at like 1300. i have the biss screw out kinda far to keep the idle up a bit from stock. when i first got the car about 6 months ago it would idle real bad after i was driving it for awhile and stall when i sat at a red light. Under normal conditions im pulling between 19-21 inchs of vac depending on idle speed. My a/f gauge and i know they arnt accurate but when my idle decideds to be a bi*** it will shut off. No reading, the vac drops to 15 the idle drops to 700 or less and i have to hit the gas real quick to save it. so if i bounce around with it for a minute it will idle fine. THe a/f gauge will bounce like it should and it will hold idle its just if im cruising around town not even beating on it and i hit a red light it will do it. However sometimes it wont. i can go all day and not have an idle problem. Even back when i got the car it didn't do it for months now its back and pissing me off. Also after long trips it allways did it when the car was really hot. a good sign that it is going to idle bad is it will start to miss real bad. have new wire that arnt arcing i checked, and just cleaned plugs and regaped. I figured the isv is shot but why would it cause it to lean out. Its like the fuel is shutting off at idle and its fighting to stay running. Hence the a/f gauge showing nothing and the vac dropping could be the isv trying to save idle. or i have a random pissed off vac leak. any help would be great. im about to just get a billit TB put a TPS on it and set the idle manually but i really don't want to dick with it.

 

[No Mo STi]

Just out of curiosity, are you running open downpipe? When my exhaust got broken off, my car would idle like crap too. And I don't think it was leaning out. I think it was running so rich that it was cutting out. I got my exhaust fixed and the problem was solved. The the O2 studs got stripped out and my exhaust keeps coming disconnected there, and the problem is back. Same problems you have. Cold idle is fine after about 10 mins of driving, anytime I'm in neutral I am watching my RPM's to make sure they don't dip below 800. When I'm at a stop light I'm always having to keep the rev's at about 12-1500. SO basically what I'm saying is, do you have a major exhaust leak?

 

[90tsidude]

not major but where the downpipe connects to the cat the gasket blew out and its leaking.