My 1998 Mustang GT has been in and out of the shop for 4 months now. I have taken it to 3 different shops. 4 months ago I took my car in to have the front rotors turned because I had shaking while braking. While there a mechanic noticed a bubble in one of my tires so I had them replace the tire. When I picked my car up there was a loud griding noise from the front end while braking. I also told them that my car vibrated now between 60 and 70 mph. They said the loud noise might be a bearing. I then took it to another mechanic and he noticed the left front rotor they turned was pitted from a bad tool. I had the original ship replace the rotor and this fixed the noise problem. I then took it back to the other shop for the vibration problem and he balanced the tires and said this should fix the problem. He never drove it to test it at 65 mph. Needless to say the problem wasn't fixed. Took it to another shop and they told me a rim was bent. Replaced the rim rebalanced tires and it still vibrates. Took it back to second shop and they told me my left tierod needed replacing. Replaced tie rod replaced other 3 tires and rebalanced tires, frontend alignment. Still vibrates. Borrowd a friends 98 mustang Gt, and changed out each of the wheels seperately and it still vibrates. I do notice a slight shimmy when I first drive off in the morning. I am at a loss here and my bank account is starting to feel the trial and error attempts. Please help.
Get into your back seat and have someone drive the car to see if the vibration is coming from the front or the rear sometimes riding in the car instead of driving can help you to identify a problem like this.
Just a suggestion have you checked to see if the driveshaft is balanced? These problems are a pain. Does it do it only at 65mph or is there a range?