Yeah, I'm sure you get this one a lot, but I replaced the IAC. I know the IAC needed replacing; it fixed the warm engine dyeing problem. But I still have a wave in the engine seems a little worse the last 2 or 3 weeks. Also, twice in the last week or so I would stop at a light and the engine would drop down to 400 rpm for about 2 or 3 seconds then back to the regular, I think about 700 rpm. And then run fine as though nothing had happened. The engine almost seemed as though it was about to die. I don't know if these are related, or perhaps a different problem.

MAF? I know what it is and where it is, but... How do you check it, clean it? Don't want to buy a new one without knowing if the old one is bad. $80 all these things add up if your not fixing the problem.

What effect if any would a bad IAT, TPS or o2 sensors have?

What's a "wave"?

I suppose a IAT, MAF, or TP issue could cause the problem you describe. Other than doing an some EEC tests I'd look at the data from these sensors.

Carefuly clean the MAF with some carb cleaner or other cleaner that doesn't leave residue.

Lookat the "Important Info" note at the top of this page about info from snap-on on MAF cleaning. Good info on correct way to clean.

Are you using your heating system when you notice this. The compressor drains power from your engine when it clicks on, which drops the rpms. I actually hear my compressor click in and at the same time rpms drop. Engine has never died. Had the idle adjusted a bit and don't notice the engine drain any more. Ford indicated it is normal.

I have noticed this in my '91 X too...but not so severe...it usually happens at night, when the lights are on and the heater is on high...if I see it happen, the voltage gauge gets pretty low too(though still in "normal" range)...I just lower the blower speed on the heater to mid and it jumps right back where it would be normally...the heater takes a lot of electricity from the alt...and that has an effect on the engine...at least in my experiance, it worked.

p.s. I have had this happen on other cars I have owned too...it's kinda similar to running an almost dead battery in the car, the symptoms are the same...