I've been having a problem with my 1999 A4 1.8T Quatro automatic (with only 18,000 miles) for several months. Often, when I bring the car to a stop from a higher speed, the engine will start vibrating. The only way to stop it is to tap on the gas. Also, recently, the engine locked up in first gear once. The dealer has been giving me a runaround. Their most recent solution has been to reset the throttle. I'm beginning to suspect that they are ignoring a serious transmission problem, and trying to wait out the warranty period. Any advice? Specifically, could a problem with the throttle have caused the engine to lock up in first gear?