I recently bought a 2006 ls coupe (5ish months ago) Currently has 115k+ on it. All fluids changed regularly etc. Was well taken care of until about a year ago..

I live in PA so it's pretty cold at the moment, and if I don't let my car warm up a good 10 minutes it will jerk and then stall out when stopping. The rpm's will also drop to about 0 then back up. This is an automatic. Also just noticed tonight that after it stalls, when i start it back up a huge cloud of white smoke flows out of the exhaust for a good five seconds or so. Doesn't do it if I shut it off myself and restart it. Once the cars warmed it drives like nothing is wrong. Any ideas what could be going on here? It also doesn't go good when cold (rpm's get high while only doing 5-10 mph, heard this happens with most cobalts though)

So far I've been told it could be the maf sensor, TB, or just my trans slipping. But it only started doing this about a month ago, and I've driven it all winter without any problems before this. Other than the random key getting locked in the ignition ha

 

Start with cleaning the MAF sensor and TB first.
You say fluids changed regularly - Motor and Transmission Oil?

 

I changed the oil at the end of November and transmission fluid about a month ago, it actually started doing this about a week after changing the trans fluid. And that just made me think, could be a bad filter?

 

My rpms dip down when I come to a stop, and will bounce back up. Goes away after I clean the tb, but always comes back. Its not so bad that it stalls but its noticeable.

 

Clean the TB and MAF.

 

Do a coolant system pressure check when it's cold,sound like a trick head gasket.
Had one once that would only leak when it was cooling down and leave a puddle under the van every morning I came out but didn't leak while driving warm.
White smoke generally means coolant leaking into the cylinders.

 

I see that you're already getting some great advice; if you do decide to work with a dealership, let me know as I want to be available to help in whatever way I can.
Sarah
GM Customer Service

 

Update on this. The weather warmed up and it had stopped doing this altogether. Yesterday it started snowing like crazy here in PA and well.. Happened tonight.

I left work and pulled into a gas station, the car lurched forward almost a foot, rpms dropped and i heard grinding.. Then it idled like nothing happened. So when I left I got my phone out to record when I stopped down the road.

http://www.youtube.com/watch?v=6k9QdsS4cGU&sns=em

In the very beginning is when it happened again, car stalled completely. Then at about 0:56? (can't remember) I stopped again, you can see the rpms slightly drop then back to 1.

I've taken it to a transmission shop and a mechanic i know when this first happened and they drove it for a week and had no problems. I'm completely lost here.

Forgot to mention this only happens the first 10 minutes or so (until it warms up) and I noticed if I'm going downhill it doesn't happen at all, only level ground or uphill.