1995 88 LSS shuts down

I have a 1995 88 LSS 3.8L that shuts down after it reaches temperature. If I put the car in park, turn off, and remove the key it will restart after a few seconds. I have recently replaced the intake manifold that cracked, the ICM, the O2 sensor, and the plugs. After I replaced the O2 sensor, the car ran perfect for 8 days. Now it shuts down on my way to work and on my way home after it reaches temperature; I have 8 miles each way. Does anyone have suggestions?

Welcome to AF. What does it take to get it restarted?

To get the car restarted, I just put in park, turn off, and remove the key. When I go to restart it turns right over and starts up.

If it stalsl momentarily and starts immediately with no hesitation, I would clean the throttle body, iac and passages. This applies if it stalls slowing down, if it occurs when cruising that is another issue, info as to how is missing.

It will shut down when just running at a steady speed; no knocks or pings, just immediate shut down.

I would suspect the crank sensor, wiring from the cps to the icm, or ign module, but unless you can put your hand on something it is a crap shoot, crank sensor first.