1995 Buick LeSabre 3.8L Intermittent Stall Then is a Crank No Start

Here are the things that I have tested - Fuel pressure is good at 41 psi when fault occurs, Alternator is charging properly at 14 V, there is spark when fault occurs (tested w/ a sight glass spark tester), engine running vacuum is 19-20 inHg, I do not have a scan tool to hook up to OBDI. I have verified injector pulse w/ a noid light, but the car will not stall/crank no start when a fuel injector is unplugged for the noid light test. The injector current waveform looks fine w/ a steady rise, flat at the top, and then drops off, does not appear to be shorted. Although, the stalling was not happening when i viewed the injector waveforms. This is all that I have so far, what could i do next? Direction?

I recommend finding/borrowing a scan tool thats OBD1 compatible and communicate with the ECM.

Not sure how many channels you have, but I’d recommend scoping ignition, spark, cam and crank. That will give the most direction. If only two channels, then I’d recommend current loops and current clamp for ignition and injectors for one channel then cam on the other.

I had a 97 Lumina that had a short in the o2 sensor harness (rubbed through on the block). I can only assume it was the 5V +
It would die, not start. Then it would start and run great for weeks. It eventually got worse and I started pulling on harnesses until it died, then pushed the harness down, started it and repeated...
A little electrical tap and we were off and running

Full disclosure this was a couple of moths tracing this down (I didn't have a scanner/scope in those days)

That 95 Buick might be early OBD2 not fully compliant vehicle. Check for label under the hood. Even if if had OBD2 standard connector under dash, it could still be OBD1. Label under hood must state OBD2 in order to communicate with OBD2 scanner