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My girlfriend said her car would jolt bad and it finally happened to me tonight while driving it. Right at 50mph when going steady at 50 the car would jolt bad. Almost like cutting in and out with acceleration. The check engine light never came on and the problem would stop whenever I accelerated faster than 50mph or went under that speed. I have no idea what’s causing it. I put the car in cruise control and slowly bumped the speed back up to 50mph and above with no problems. Help.