My car kinda sputters randomly and then the speedometer surges up to over 100mph and back down real fast. It doesn't seem to be electrical as lights and radio are fine. Doesn't seen to be transmission as it switches gears fine and doesn't lose power going up hills etc. It happens when I'm either going fast or slow. Sometimes I can go 30 miles or so and it won't happen. When it sputters it doesn't seem to lose power. A few weeks ago I had trouble starting it when I used the radio for about ten minutes with the engine not running. Not sure it that is related. Also, before this started happening the fix engine light was on, but now it's off. Not sure if that is related to current problem.