No, I really can't say I have. Well, no, my car DOES do it when I first turn it on cold. But I've also got a pump somewhere going bad. My power sterring pump I think. It makes this AWFUL groaning noise for a minute or so until it warms up slightly. Sometimes a bit longer. I noticed the other day that it was really hard to steer while that was happening. The car also REALLY wants to get up and go. With my brakes being crap, I have to really push my foot down to keep the car steady. Anyways, if I let it idle, after a short bit at around 1200, it keeps dropping down to around 700-800, then back up to around 1200 and back down. Vrooom Vroom Vroom. You get the idea.