What is wrong with my car?
My 91 Beretta Gt started to vibrate only at high speeds but now vibrates at almost all speeds. It doesnt do this all the time though. now that it is summer and i ride with my windows down I can hear a huge difference between when its vibrating and when it is normal. Something seems to kick in and my car rides normally again. It sounds like i stepped on the gas with the car in neutral when this happens and the pressure in the gas pedal comes back and the speed and rpm goes up quickly, but when vibrating, well it sounds like vibrating and the whole car shakes i can push the pedal to the floor but the acceleration is really slow. New tires, rotated and balanced, the engine is mounted well, suspension is tight, and i have the best synthetic oil Mobil one has for high mileage and a new oil filter. Its at 98,505 miles. Its getting really expensive trying to find the problem. Please help me if u can.