93 Cadillac STS, with northstar engine. Stalling problem

OOOps. The first part of my problem description was posted before I was finished. Sorry.

So, to continue…the first mechanic said that, quote “The PO83 code is a Speed Sensor Code and will not effect performance or cause a stall”.unquote. The second says that he can’t know for sure until my car stalls and will not restart. Is there anything else I can do? Any suggestions? I need my car but I’m afraid to drive it for fear of stalling and causing an accident. PLEASE HELP> Thank you.