On my way to the dealership today, my car started acting REAL funny. It's still cold here in MI, so I let my car warm up for a couple minutes before driving, then I drove it carefully, not hard at all, to the dealership. About halfway there, I'm stopped at a light, and I start hearing this helicopter type sound. I was right next to the hospital, so I thought that there was a helicopter flying overhead since they're constantly leaving and going from the U of M hospital. I didn't see one, but then I realized that it was my car doing this. I hit the gas a little bit and it feels like the car wanted to stall. It didn't rev up at first, then didn't go up smoothly from there. The car was sputtering pretty badly when I first started going from the stop in the low rpms, then got smoother over 1500-2000 rpms. I pulled over as soon as possible in a parking lot to check out was going on. It still sounded a lot like a helicopter. I put my hand by the exhaust and felt pulses of air coming from it. I checked out the engine and it was shaking pretty bad, trying to stay on at idle. I turned the car off and let it sit for a minute. When I started it back up, everything was all normal again. I have no idea why it did this, it's the first time that it's happened to me. No warning lights or anything like that came on. I told the dealership about it when I got there, the mechanic 'investigated it' but didn't know what it was all about. So I have to tell them if it happens again before I bring it back Thursday to get more details about what happened. It was pretty strange...I don't know if it was because of the cold or what, but have this happened to anyone else??