1992 3.1L MPI starts, then stalls as it warms up

[rhoptry]

We've been having this trouble. Starts fine, but shuts off way before the fan comes on. Shuts off about the time it would be going into closed loop. New plugs and wires. Cleaned the IAC. 1992 Lumina 4-speed auto, 110,000 miles

I'd appreciate suggestions on what to test or try.

thanks,
Dave

Gaithersburg, Maryland

[robertisaar]

Shuts off about the time it would be going into closed loop.

you may have answered your own question. O2 sensor.