Hesitates, shakes and back fires

My car has a hesitation and stalls. It all started five days ago and I have not driven it more that a few miles since. It starts to hesitate anytime after about one mile of driving. It has stalled on me four time time, all after the car has warmed up. The first three were within about half a mile. Also, when looking over the engine after the stalls, with no on in the car, it revved up then wanted to shut off. It does this several times then idles smoothly for a minute or so the repeats. We change the spark plugs and are considering changing the coil packs. Do you have any suggestions we can look at first?

Thanks,
Rick

The car starts fine and drives fine but some times when slowing to to stop at a light to make a turn or just to stop because the lights red it will act like it wants to stall but does not, when this happens the headlights go dim. It only happens sometimes and the GM people checked it out and do not know. I changed the IAC and cleaned out the throttle body.(Well the people at GM did). I cleaned the battery cables and changed the battery. It still does it. When sitting it idles fine. It is just after driving and I start to slow down it will do it. It does it when I take my foot off the gas.

No there are not. Just the ABS but that would not have anything to do with it. I would give money on here if I could, but I do not have a card, lol. Or much money because GM charged me $425.00 for that. My Oldsmobile has a 3.5 twin cam if that helps. This only happens to me when I am going 30 mph or under.

Yes it is. I just had it off and was checking it out yesterday. This is on odd one is it not?

My car was running poorly during fast acceleration and at speeds over 60 mph. I had the O2 sensor replaced and the MAFS cleaned and re-calibrated. The car ran perfect for about three months. It started stumbling again. I replaced the MAF's with a re-manufactured one from the parts store. Service codes were reading P0031 and P0037. While sitting in park and flooring it, at exactly 4,000 rpm the engine cuts out and falls back to 3,700 rpm, then races back up to 4,000 to cut out again, and cycles like this until I let up off of the gas. The car runs okay while at 30 to 40 mph as long as I do not try to take off quickly. But if I floor it, forget it. It stumbles badly until I let off the gas. Same at highway speeds over 60 mph. To go over 60 mph I have to floor it and hold it there. Any ideas? No other codes reported from my CP9580. Thanks!

3.5 twin-cam.

How can I see that bigger? Is there a URL or anything? What does it mean if your coolant reservoir has almost topped itself off. I was just looking at it and I remembered it last week seeing quarter filled where it is meant to be. Now it is almost filled and I added nothing to it. And the car has been siting for six hours.

What dos that mean? Bad thing and probably should find a ride to work in the morning? Lol

Well, I took if for a drive five minutes ago up the road and it filled up more. The car did not seem to get as warm inside as fast as it did, but I do not know. It maybe just trying to understand what is going on.