While I was driving on the highway, I accelerated to 55 mph but suddenly the car decelerated to 50 mph. I tried to increase the speed to get up to the speed limit, but the car wouldn't increase the speed and the rpm would continue to climb (maybe faster than normal. I quickly pulled over. The RPMs were very inconsistent and I couldn't really drive past 40 w/o this problem.
My car has 165000 miles.
My car has an automatic transmission.