1997 Chevrolet Lumina

The car is a 1997 chevy lumina (ls?) 3.1L. V6 119,000 miles

the past few days, while driving after little over 12 miles it seems, or when engine gets to the normal heat level, my car just dies out. The lights and everything work fine so it is not the battery. The rpm bounce up and down while im pressing the gas then it just dies.

today after a period of a few hours of waiting in the cold trying to figure out what im going to do, I tried my ignition and the car fired right up and drove fine for about 15 miles. It happened a few days before and I had the fuel filter replaced, I added some fuel injector cleaner and 4 gallons of gas and it ran fine all weekend. Then monday it started happening again on my way to work.

i noticed that it seemed much worse with less gas since I drove it fine all weekend with over a half tank, then when it got to a 1/4 tank it started to happen really bad. Every time I had to stop at a stop light or stop sign or any place, the car would die, it wouldnt start at all in park, so I put it in neutral and it would start fine and drive ok until the next stop, where I had to put it back in neutral after it died and start it back up.

my mechanic doesnt know what to do, since its hard to get the car to him while its having the problem, and its also an unpredictable problem since it doesnt do it all the time. Any suggestions? TIA for any help. Im going to take it to a new mechanic tomorrow and hopefully he can hook it up to something and run some tests.
November 19, 2007.

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