1993 Mazda 929

Engine Performance problem
1993 Mazda 929 6 cyl Automatic 145, 00 miles

Im having problems when I initially put my car in drive and begin to take off. Everytime I slightly press down on the gas my car gives me a jerk. Whenever I press down firm on the gas it doesn't do it until I get around 40mph and then it jerks again. Also whenever Im at a desired speed I can't just leave my feet on the gas and the car just cruises. It instanty starts jerking as if Im repeatedly pressing down on the gas like Im playing a drum set with my foot if that makes sense? Whatever is going on no one has had a solution for me. Not even Mazda. I have no engine light on. Can someone please help me? Thanks in advance.
August 18, 2010.

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