Pontiac Repair: Miss fire 95 grand prix, chevron techron, spark plug wire

Question
It has trouble starting. Idles rough and rpms are high then go back down . When it goes over 45 it shakes and vibrates until i let off or the rpm go back over the two mark. 3.1 v6 grand prix se. Id really appreciate the help  

Answer
Hi Arialle:

well the misfire can be something as simple spark plug wire that is arching or a bad ignition coil that has a bad connection between a wire and the coil it's self.. It could be a dirty fuel injector. If you have a dirty injector you can try an product called Chevron Techron injector cleaner you add it to the gas tank.. As far and the idle issue it can be a dirty throttle plate and or idle control motor on the throttle body. It could be a vacuum leak as well. With out seeing this it's hard to give you an exact reason for the 2 issue you have. when was the last time this car had a tune up plugs,fuel filter etc?? Has the service engine soon lamp come on? Good luck :)