OK, I'm new at this and just read through TMSCHERR's posts on his 91 Chevy Lumina stall problems. I am in the same boat it seems, maybe worse. Also, I need to be super frugal and wise because I'm on SS income.

Here's my problem(s).
First few days - car started to stall @ lights now and then. Kept going tho in neutral. Idled fine. Service Engine light came on only once when car was still on, and for that I pulled into service station and turned off the car. When I re-started, the engine was on high rev and wouldn't come down. Restarted again, and it was OK and no more service lights have come on (except each time it stalls and they all come on).

Next few days - started also stalling sometimes going down hills or when I deceleratted.

Mechanics put on scope - nothing. checked fuel pump, changed spark plugs and wires, checked for v hose leakes; changed out 02 sensor , cleaned fuel injection system and put in a cleaner, checked (by trading out?) MAP sensor, checked TPS. Only could find car was "running rich". Wouldn't stall for the mechanics (of course not) . Sent me home.

Car ran fine that day. Next day car died once at a light, restarted fine, was running a little 'high,' but not much. THEN when I was doing 65 on a crowded freeway, I looked down to notice the motor had stopped! I pulled off, restarted the engine and gunned it to get back on the freeway but noticed the speedometer was not moving off "o", so I pulled over, stopped and started engine again. I pulled out and the car drove the next 13 miles OK to get me home. Speedometer was OK again. Only thing I noticed were slight "surges" now and then on decelerate. THAT's IT!. I'm not driving till it's fixed!

I was hoping Tmscherr would find the cause and I could piggy back off that. What a time for him to be in the process of moving. Anyway, sound like the same scenerio? Any suggestions? How do you "check out" a MAP sensor? Thanks.

I would start by changing the crank position sensor. Common problem on these cars, less that $20, and easy to change.

To test the map sensor all you need is an ohmeter and a vacuum source. Its like a vacuum controlled resistor. High vacuum = high resistance, low vacuum = low resistance.

I would probably go with the TPS though. When mine went bad the engine ran up nearly to redline sometimes if I would so much as touch the gas pedal. The engine would also surge when I let off the gas if I was allready driving. This could also cause an intermittent stalling problem like you are experiencing.

After much debate and many items tested, I decided to change out the main computer. I have been driving for a week with no stalls, so it seems to have solved the problem. Thank you for your responses. It's been a huge learning curve.

what exactly does the crank position sensor do?

It tells the ignition module when to tell the coil packs to spark.