This all happened within a couple of miles of driving home. First the air conditioner stopped blowing cold air. Then the battery light came on. Then there was some white smoke. I had to stop the engine at a store. When I started again, the engine almost didn’t turn over but it did start. But the idling was high as I left the parking lot. The final half mile home, the engine was jerky and the speedometer was stuck on 55 mph no matter what the actual speed, and the RPM was stuck on 3 (30,000?) no matter what speed.