83 Cadillac stalling issue

Did the trans concern and the stall come on at the same time? It sounds like you possibly have two separate concerns. When the vehicle stalls, and won't start, pull a plug wire and check it for spark output. To do this, you want to use a screwdriver inserted in the plug end, hold it close(1/8 to 1/4") to an engine grounding point, and crank the engine. If you don't see a spark, or feel one as you will if your gap is too large, you have a no spark condition. I would initially suspect a faulty ignition module, with that result.

But have you checked it for spark when it won't start? You are losing something to cause it not to start.