I bought a 99 obs about three months ago and its been giving me some funny problems.  the cars got 260k miles and im looking to get another 100k at least.  Luckily its the 2.2l but when it warms up it feels like it wants to stall at idle.  drives great and idles fine at first, but after sitting for maybe 7 seconds the rpms drop from about 500 to between 250 and 300.  The car and engine shake really bad and it sounds like its running on two cylinders.  I recently replaced the spark plugs with bosch platinums but didnt happen to check the gapping.  also the wires were changed at about 160k miles but they are not oem. checked all the hoses I could see and didnt find any holes or cracks and just adjusted my throttle cables which fixed my cruise control issue  but still no luck on this darn idle.  any pointers would be great! also i dont know if it could be related but I put a cai on it and didnt want to run at all.  Maybe faulty MAF sensor?

any CEL codes?

 

possible engine temp sensor or knock sensor problem. Most other issues might set a code.

the guy I bought it from said he just changed the knock sensor but I dont know. And thetre are no codes, and i n this case I wish there were. It would at least give me a starting point. and I paid closer attention to the tach, it pauses at 1k for a sec then drops rapidly to about 500 to 400.

First thing is to is get rid of those damn platinum plugs. They are a complete waste of money in that car. The $2.49 NGK standard copper plugs work the best. Gap at .039"

 

Second get some new plug wires. The old 2.2s aren't too picky about brand as long as they aren't the cheapest of the cheap. Ive used Standard Ignition, and Carquest house brand in both of my cars and have no trouble with either brand.

100k miles is about the lifetime of a set of plug wires, so even if they don't cure the problem they're still a good investment for reliability.

Did the plugs and its a little better.  I'll get the wires tomorrow.  The coil packs don't usually go out do they?  

could also be the Idle Air Control as well. Might pull it off (if its the on top intake style with hose going to port) and clean it out real good. 

Thats what I thought it was at first too.  I have already cleaned it and the throttle body out really well though.  I gotta wait to order wires till I get paid since I'm getting NGK, but I thought about cleaning the egr valve.  I couldnt find it on my engine but the autoparts store says that I have one.  Anyone know where it would be on a ej223 engine?

I might just be throwing answers at this thing, but i noticed that as I come to a stop I have to break harder at the lower speed when it shifts down, I also read that a bad vehicle speed sensor can make breaking more difficult and controls some of the fuel/air mixture.  However my speedometer works just fine.  Any thoughts?

*Bump.  Also now my . cruise control doesnt work again.  It tried to work for a sec the other day and shut itself back off, thinking and hoping they are connected somehow

Cruise control has its own vacuum pump so isn't really connected to engine running. However, if the CEL is on the cruise will be disabled. If the CEL is on get the codes scanned. If its not on make sure the bulb works during the bulb test. Turn the key to ON, or Start the engine and the CEL should illuminate for a few seconds then go out.

 

Also just noticed you said you put a CAI on the car. Are All of the original breather hoses and the hose for the IAC connected to the CAI tube?

Is the MAF sensor plugged in?

If the idle motor shorts it drops injector pulse on #1 cly check idle motor and its conections

All the hoses are connected, and thanks for the heads up on the CEL.  I had it fixed for a bit since the guy before me gutted the cat, but adding one of the little spacers only turned it off for a couple hundred miles.  Anyone know if theres a perminant way to turn it off.  I dont havbe any codes for the ropugh idle, but I adjusted the tps the other day and its made a world of a difference.  Luckily I have the 4 wire TPS so if what I read is right the engine won't re-learn and adjust the idol again.