Hello I have a '94 Mercury Coougar XR7 and I am having a serious problem with my whole car shuddering. A diagnostics test showed everything is O.K.. it has always had a little shudder when I took off from when I bought it used about 6 years ago. But now it has gotten so bad that it does it all the time. When the engine shifts gears the rpm's go down of course, but the shudder goes away for a second. We think that the harmonic balancer has slipped on the rubber seal that goes in between the metal of the weights themselves. There are 7 cracks in the rubber itself. I have just taken the harmonic balancer off and started it and the problem is still there. Now we know the balancer was off of course, but ait seems like there would have been a differance of some kind. The shudder is real bad in lower gears. It is an automatic transmission as well. I thought it might be the torgue converter at first. I am baffled. HELP PLEASE>

 

torque converter would be my first guess too.

 

Check the balancer with a timing light