93 Mustang 2.3L LX - stalling, etc...

My problem is kind of hard to explain (especially since I don't know much about cars). Anyway, I bought it almost a year ago. At first I had a problem with it overheating, fan wasn't coming on without A/C on. A mechanic friend of mine found the coolant sensor was bad and unplugged it so the fan would stay on until I got a new one. (Haven't gotten a new one yet as it was running fine). After I had it a couple months I began to have problems with it starting warm. It didn't always happen, but when it did I would have to let it sit for an hour or so before it would start. My friend hooked it up to the diagnostic and it showed nothing, and can't replicate the problem. So after doing that for a few months it started stalling at highway speeds. Very rarely and again can't replicate. Now, still having the no warm start problem, and the stalling has gotten a LOT more often. It doesn't seem to have any pattern to it. Has stalled at idle and at 70 mph. Doesn't want to start for a while after it stalls. I've noticed recently that the rpms seem to bounce at idle between approx. 600 and 800 rpms. And on acceleration or deceleration it seems to "miss" and then catch the shift. It stalls when it doesn't catch. It doesn't sputter or anything, it's just as if I turned the key to off. I can't figure out what's going on. And still can't replicate it to find out what's going on. When it does do it, it starts up again by the time anyone who knows anything about cars is around. :banghead: Does anyone have any ideas on what the problem could be or even on how to get it to replicate? We've checked the fuel pump and it seems to be fine. And we've checked the coils, and we get a spark, but again only been able to check when it's running fine.

This is just a wild guess here, but you may have a vacuum leak. I am thinking it could be your timing sensr which sits behind your harmonic balancer. It it is off or broken, you should replace it and your harmonic balance. Also check your Mass Airflow Sensor and the ECU/ECC

It sounds like your mass air flow sensor is going bad. Try starting your car open the hood and tap on it. It is located next to your air box. If your rpm's change when tapped on it is going bad.