Lowaholic

Hey all, sorry about the long post but I'm desperate here... Any help on this is VERY much appreciated. Here's a list of the things I've done so far to try and track down the cause of these problems:
-new plugs,wires,cap/rotor,ign coil
-new O2 sensor
-rebuilt the TBI with all new gaskets/seals
-measured inlet fuel pressure, = 11.5 psi
-measured idle vacuum, = 20Hg, reasonably steady
-checked EGR, ok
-checked TPS, ok
-checked all wiring, no probs found
-swapped in another ECM, no difference
-here's where it gets weird= when I disconnect the MAP, the idle straightens out but it's still hard to start. Also without the MAP it wants to stall after a few minutes of running on its own. Could a bad or weak distributor module cause any of these symptoms? I'm almost out of ideas here... Thanx again for any replies.

MONTYR1

Maybe try replacing your map scensor Try picking one up at the junker it wont hurt the pocket too much if it doesn't help. Hope everything works out. let us know if it worked.

Lowaholic

nuts- i forgot to mention that. Yeah, I tried two other MAPs- I had an old one laying around and the one out of my girlfriend's S-10 (same GM part# as mine). With any of the 3 sensors connected it went back to doing the same thing. I guess the next step is to check the alternator and the EST/ESC modules just to be sure... Thanx for the help