I have a 1997 Mazda mpv that vibrates on the highway. It drives fine in the city but as soon as you go over 80k it vibrates and I have had the tires balanced and the rear drive shaft balanced and it still vibrates. Please help??

check the timing belt

Check your air filter

no not typically. Have you checked out the tires closely for any signs of tread separation on the tires? That could be associated with the vibration above 55.

I would start by checking the tires for balance or bad belts

Have you cleaned the throttle body bore and plate of any black carbon ? The idle air control circuit may be clogged or the IAC may be stuck closed .

Yes at 100,000 miles

Balance your tires,maby the problem.

If you drive normally then change your oil/filter every 5,000 miles. If you drive mostly city driving change it every 4,000 miles. If you drive mostly highway then change it every 6,000 miles. If you are using a synthetic oil then add 1,000 miles to each of these intervals. Use the correct weight oil for your 1997 MPV as listed in the owner's manual. Also use a quality filter such as Purolator, Wix, or Bosch. Change your air filter every 30,000 miles unless you drive in dusty conditions and then change it more often.

yes they will

I'm pretty sure that your front rotors are warped. Is tis problem only happening when you apply the brakes? If it is, replace the front pads and get new rotors. Be sure when you install the front tires back on, torque the wheels to 90 lbs.