My 91 Grand Prix is having some issues. On start up, it will rev really high for about 30-40 seconds. It will then go back down to regular idle speeds while its still in park. As soon as I shift it out of park though, it will start shaking and sputtering until I step on the throttle. When I open up the throttle going down the road, it will do just fine at normal speeds. But when I start to slow down to come to a stop, it will start acting up again. When I come to a stop, the engine will shake for a few seconds, and then promptly die. Any suggestions?
