My mark acts like it wants to shut off when im in drive and stopped at a light, and the lights dim a little each time. In park its fine. Its a 96 and it idles around 100 then jumps to 200 the back down every second. Whats up?

First guess is the Idle Air Control valve, aka, IAC. If it was across the RPM range I would think something else, but only at idle right?

Yeah, sounds like either a problem with the IAC itself, or a problem with the TPS (throttle position switch) making the IAC not operate.

Yeah. only when its in drive and stopped. How do I fix it?

Well on a Gen I its a little bit of a pain to replace. The TPS is in the same neighborhood.

So you can do two things. Take its all apart and replace the IAC and hope its fixed. Since your there, replace the TPS also.

Or you can take the IAC out, clean it, and put it all back. The thing is the IAC may work fine but they do not like cleaning and may not last long. So you would have to dice back in and replace it.

On a side note. My roommates continental had a bad one. Oddly the car idled fine. When we disconnected it, it did not stall as it should have. Cleaned it up, same thing. So we replaced it. Now the car runs better and it responds better to the throttle. Just and FYI.

Try tapping on it with a long screw driver or something. It just may unstick it. One morning about a year ago my idle was very low so I tapped on the IAC with a long pry bar, ever since then it's been fine.

It might work?