1997 Pontiac Firebird Car Stalls after 30-45 mins of Drivin

Firebird runs great for 25-45 mins then stalls out. And will not start (no spark). No Code(s). Only "Check gauges light" . But nothing else.
Let sit for 30-45 mins starts up and runs for about the same amount of time.
I have just found out that is has been going on with the previous owners but not as bad. It seems the more I fixed the worst I have made the stalling condition.
Something is sending a signal to shut down the ignition. But there is a lot of Wiring and Sensors. See my delema.
The only real fact I know is it will run longer in the cool morning than in the hotter afternoon.
Replaced: Key Cyclinder, ECM, BCM, EGR, O2 sensor, catalytic converter, fuel filter, 2 coil packs, spark plugs and wires, Water Temp sensor, Thermostat.
The Ignition Control module checked GOOD (when Cold). Tried heating ICM up with a lighter but still checked Good.
So, can someone tell me exactly which sensor(s) or Module or Wiring would shut down the ignition. Thanks