Im from miami so after Hurricane Wilma gas was not easy to find now, I went to a station and fueled up from empty then as I headed home i noticed a strange vibration at around 2000 2500 RPMs, The higher the rpms got the faster the vibration, it also makes a sound similar to rolling your tounge. At first i figured it was a bad batch of gas so I got some water remover, and nothing. I also hear a thunk when I accelerate which i think is the tranny mounts. I really cant figure out what the heck is causing the car to do this. Can anyone help? Ben3rd@netzero.com
Thanks,
Ben

I would check u-joints first.

That's my guess........

i have the same problem.....have you checked the spark plugs?

Do the crayon test on the driveshaft. Jack up the rear of the car, and place on jackstands, with the front wheels blocked. Have a buddy get inside the car, start it, and put it in gear. Get underneath the car with a crayon or wax pencil, and as the driveshaft spins, let the crayon draw onto it, making sure your hand position holding the crayon doesn't move. When you've drawn a full circle arond the driveshaft, have your buddy let the RPM's go a bit higher and watch the circle. If it jumps out a little bit, you have an unbalanced driveshaft. Do this at 3 places on the driveshaft. Front, middle, and back. If you find an area where your crayon drawing doesn't spin perfectly circular, you can be cheap and attach a hose clamp to the driveshaft to correct the balance. Make sure the adjusting part of the hose clamp is placed over the area of your drawing that jumps out of round. Don't use more than 3 hose clamps, and this is a TEMPORARY fix only. But as stated above, also check your U-Joints for any play.

.....jack up the rear of the car, and place on jackstands, with the front wheels blocked. Have a buddy get inside the car, start it, and put it in gear. Get underneath the car with a crayon or wax pencil, and as the driveshaft spins, let the crayon draw onto it,............

Sounds like an interesting test, but I think he'd be a whole lot safer to do this on a real lift.

Just my $.02

Probably... ;) I don't have access to one, and most don't so it was the first thing that came to mind. But by all means, if you have access to a two post lift, go for it! Even better, you won't have to get your shirt dirty! Good luck...