REALLY need help! Please?

I have a 1990 Pontiac Grand Prix, 3.1, overdrive, and about 200k. Recently, it has developed a problem. It will die and is impossible to restart untill it cools down, mostly when under load or at operating temperature. Here's a list of what I've done/checked:

1. Replaced spark plugs
2. Checked wires-OK
3. Replaced dirty air filter
4. Replaced clogged fuel filter
5. Replaced howling fuel pump
6. Checked for fuel leaks-none found
7. Replaced all 3 coil packs.
8. Fixed numerous vaccuum leaks
9. Checked MAP sensor. Held vaccuum. Replaced with a known good one-no change.
10. Cleaned IAC motor. No change. Unplugged IAC. No change. Replaced IAC. No change.
11. Checked IAT sensor. Passed
12. Checked coolant temp sensor. Failed. Replaced. No change.
13. Checked crankshaft position sensor. Passed.
14. Cleaned digital EGR. No change.
15. Cleaned throttle body and passages. No change.
16. Replaced ignition control module. While it runs better, the problem still persists.
17. Replaced TPS sensor. No change.

The car will start and run fine when at idle and cold. However, as it approaches operating temp, the more grumpy it becomes. When cold, you can increase throttle, but only to a point, and then it will die. Also, if you increase the throttle too fast, it will die. When the engine reaches operating temp, the slightest touch of the throttle will cause it to die. In any case, you can not restart until it has cooled down. Almost acts like it's flooding out. Pressure regulator? Any help would be much appreciated.