Rx7 weird idle
 

I guys, i was wondering if somebody could help me. I just bought yet another 88 rx7 vert and it has an odd idle. After it warms up a little bit it will start surging but only a couple hundred rpms and if i turn on the a/c it goes away. Does anybody know whats causing this? Any help is appreciated, thanks.

First guess is a vacuum leak. Closely look at any hoses or gaskets, including the intake manifold gasket, after the throttle-body.

those were the first things i checked and all the vacuum hoses look fine and i sprayed around the gaskets with carb cleaner and couldn't find anything. something else i just remembered too is that i don't think my brake booster is working, i'm not sure though because i haven't even really driven it.

You always want to make sure that the TPS is set properly. The Green/Red wire w/key to on should read 1 volt after the engine has been completely warmed up (20 minute drive).

Agree with satch. May not necessarily be your case but if idle isn't set properly may cause some minor issues.

My car would surge being out of adjustment as it sat on the line of the ecu advancing timing. The timing is static from idle to 1100 but advances after that. Consequently my idle was stuck between 1050 and 1200 until I reset my tps and idle.

also make sure that all the grounds in the engine bay are clean and in good contact. If you havent already, check the ECU for trouble codes if there are any

thanks for all the input and i went through and checked all of that like you guys had mentioned and everything seems ok but while i was messing around with the car i noticed that it has no power brakes and it wouldn't warm up hardly at all which i found out trying to do the test mentioned by satch since i haven't really driven it before then. found out the guy had removed the thermostat so i put a 170 degree thermostat which is 10 below OEM in and it still isn't heating up much at all, just to the line right above the c mark. so i was just wondering if A) the brake booster issue could contribute to the idling issue and B) if that 10 degree difference would keep it from heating up that much and if not what could be causing it?

Well i got to tinkering with it a bit yesterday after getting back to va and i still couldnt find the vacuum leak so i just said forget it and took it for a drive and while driving it just randomly quit. Went out and drove it again this morning and it idled fine the entire time. But a new question is that since i replaced the thermostat again the temp went up higher nut it still isnt as high as my other vert sets normally. Im just wondering if this is the normal temperature or not. Ill have to email/pm you the picture because i cant upload it on the post.

1/4 to 1/3 is normal. And this is w/a temp gauge/temp sensor which is accurate.