Engine Performance problem
1995 Mercury Tracer 4 cyl Front Wheel Drive Automatic 137000 miles

Im getting a rumble as i accelerate in my 1995 mercury tracer seems to start at around 25-30 mph. when i get of the gas and coast, it stops. I have had the tires rotated and balanced the fuel filter replaced and an oil change. 2 of my my rims are wopped. I had those put on the back. My driver side tire is loose from wheel barrings . I would like to know if you could tell me why it is bouncy upon excelleration

thankx