I have a 2000 ford mustang v6 with a 3.8L. The other day while I was driving the service engine light came on. Soon after that the rpms began jumping, the car lost some horse power, a mist started when idling, and the fuel economy got really bad. Well I took the car to a local mechanic and they put it on a computer and it said that the throttle position sensor was the problem. So I buy a new tps and it still isnt fixed. What to do?