1994 Oldsmobile Cutlass Stalling, need help!

It sounds like a classic symptom of a torque converter clutch solenoid that is sticking on. There should be a four wire connector on the trans, with two wires, a purple, and a tan w/black. Disconnect it and drive over the same conditions that would make it stall prior, and see if it stalls. The connector is for the TCC solenoid, and you are preventing it from coming on. The transmission will act like a normal three speed.

When it stalls like it does, what happens if you shift to reverse, do we still stall, or perhaps even neutral when it tries to stall. Has the fuel pressure been checked? The fact that it will start and run until it is put into gear, leaves few variables. I would have to speculate something in the transmission. If it does it in reverse as well, this would validate it more. In sputtering and stalling, I would not feel it was electrical. If the fuel pressure fades out while under load, I don't know why you would not have other driving related issues, other than idle at stop. Is there ever a check engine light on?
Looking at service information, there is no symptom related diagnostic for stalls at stops, in gear. The fuel pump control circuit does include an oil pressure switch, but it's job is to keep the fuel pump running when the relay, or PCM control of pump fails, and the oil pressure is still above 4 psi.