Car starts fine..once the engine gets warm..the idle drops to the point where it almost stalls..then the idle jumps right back up. It does this while driving and while just sitting in park. Vaccum was the first thought..looks good. Next the throttle body gasket was checked and replaced. Still no fix. Distributar(sp) cap and rotor were changed next. Wires also. No go. Engine still does the same thing. Im at a loss guys..help me out.

Same problem here... It's only when the car gets hot.

Sounds like a dirty IAC....yank the throttlebody and clean the bores and everything very thoroughly. That should take care of it.

Mine just started doing that after prom recalibration... didnt do it before. Also wont start good after it gets hot...

What's IAC?

IAC = Idle Air Control, it is the little motor on the bottom of the throttle body.

There are alot of things that can cause this, dirty IAC, TPS sensor going bad, lazy O2 sensor, injector o-rings leaking unmetered air (vaccum leak), check to see if you are getting any engine codes out of it and start there.

Mine is doing the same thing. If you get it solved, let us know. I will try those few things too and see if that works.

By the way, that is a nice 89' Formula. What does it run in the quarter?

I have a extra IAC and 02 sensor if you want to try them. It is more than likely one of them. If you want to stop by we can throw them on and see if it takes care of it. 558/6694

Got my idle problem fixed! I ended up breaking down and bringing it to a shop to diagnose it. Set me back $90 stinkin bucks!! Turned out to be that the base idle was out of spec. All he did was adjust the little set screw. I would've never guessed it was the idle because it seemed fine, it just swung back and forth and was rough. But he told me that the computer is trying to make up for it to keep the car running so that's why it swings back and forth. Cleaning the IAC and TB passage-ways also seemed to help. Give it a shot and let me know what happens.

However, my car still doesn't start when hot, and I even just replaced the starter cause the guy told me my starter was not cranking fast enough. Any ideas on the car not starting when hot? The guy said everything looked fine, gas, electrical, etc. So what's up here??

Sorry, turns out it wasn't the ignition module. The car still does not want to start. It did the other day, but now it's not when it's hot again.

But, the idle problem was in fact fixed and it is no longer swinging back and forth. Make sure your base idle speed is to spec, which is apparently like 800 rpm or so..

Yay third gens....Hot engines to help with emissions and burn more gas....Very hot engines make starter solenoid not work properly.....Answer move the solenoid and install a remote starter solenoid....go to thirdgen.org they have a tech article on how to do it....you can even use it as a good excuse to install a push button starter!!!

seems it was my o2 sensor. Im gonna have to give ya a call one of these days chris...working like crazy..