I have a 2001 pontiac grand prix gt with a 3.8L N/A motor w/ 120,xxx miles. A FWI, glass pack res, 180* T-stat, flowmaster mufflers. I recently changed the PCV valve, spark plugs and wires(factor AC Delcos), changed the oil, ran seafoam and Chevron fuel system cleaner. Changed the fuel filter, did a radiator flush and replaced the radiator(unrelated repair), replaced the throttle body inlet screen since I broke the other one attempted to clean the throttle body. All of the wires are secure and the idle(RPMs) aren't surging at all but the car has a very strong vibration, I inspected the top 2 mounts and they seem to be in working order and driving I feel no loss in power and there is no hesitation so I have kind of ruled out a fuel or spark problem. I believe I have tried mostly everything except for replacing the two easily visible mounts. Has anyone else had this problem or can someone recommend the next course of action I should take(I am trying to avoid a trip to the mechanic, I'm not trying to pay for him to guess the same way I did). Any help will be greatly appreciated.
Thanks
