Ford Repair: 94 Ford Mustang 5.0, autolite plugs, ford mustang

Question
Hi, I have 94 Mustang 5.0 with a problem that I can not figure out for the life of me. I have an intermittent misfire that has been plaguing me for the past 8 months or so. After looking around online for a little while I tried a few things, I'll try to explain in good detail what I've done since I know it could be many things. First off, as I said, about 8 months or so ago I noticed an occasional misfire. Seemed to happen only at low RPM, as soon as I go wide open throttle it disappears, full power.  Started by doing an MSD ignition upgrade (including 8 Autolite plugs, MSD wires, MSD coil including TFI harness, MSD 6AL box and MSD cap n rotor). Problem stayed. I then replace the TFI/ICM, problem still stayed. One day the car shut off and would not start again. I got a junkyard distributor off an old F150 5.0 just to test the Pick Up/Hall Effect sensor. Car started right up, ran about 10 mins, went for a 5 min ride and it shut off again. I then ordered an MSD distributor since the junkyard sensor worked at first. After installing the new MSD distributor the car started right up and ran better than it ever has for about a month, until today. Same intermittent mis showed back up. I was happy to make it home and parked it. The car still starts and drives but I'm afraid to run it to much because I want to find the problem before it shuts off again. Check Engine light comes and goes with the mis, never stays on long enough to check the OBDI code. This engine has about 80,000 miles on it. I bought the car off of a good friend of mine a little over a year ago. He drove it everyday with no issues. I buy it as a weekend toy and all this starts. Luckily it's not my everyday driver. Any ideas? Thank You in advance. Sorry for the length.

Answer
First thing I would do is check for codes. Even if the light goes out, most things that will turn the CEL on will store a code in memory, and the code may lead you to the cause of the issue. Personally, I would put everything back to stock until you figure out what the problem is.
Intermittent misfire can be a lot of things, just a matter of narrowing it down. The stalling sounds like a different issue, checking fuel pressure and volume would be a good start for that complaint.

When replacing ignition modules in this vintage TFI system, it's best to use a quality part. Too many are imported and not to Ford specs, or as durable as OEM.

See if you get any codes and let me know if you do.