1990 Oldsmobile Cutlass Shuts off, stalls, turns over but w

Engine Mechanical problem
1990 Oldsmobile Cutlass 6 cyl Automatic 126000 miles

I've tried just about everything with this car. I've had this car worked on for the past 2 years. Just when we think the problem is fixed it comes back! It used to be that when you drove it on the freeway it was just fine but when you're city driving (a lot of stop & go) it tends to stall when @ a light. Now it will turn over for a second and then shut off. So far we've replaced the alternator, heater core, radiator, replaced ALL sensors, battery, spark plugs & wires, fuel tank, fuel pump, air/fuel filter, catalytic converter, ignition module, motor mounts, brake booster, idle throttle, and the fuel pressure regulator (putting new o-rings in recently to see if that would help). No codes come up on the computer scan. So with all this new stuff in the car you'd think it would work right?

Also, I don't know if this plays a part in the problem but the electronic dash turns on and off whenever it pleases, it seems to respond to temperature, and the left brake light doesn't work anymore even after i've replaced the bulb 3-4 times. I've looked around on the web but couldn't find anyhting specific for my situation. Please help if you can, thanks!

-Danika