Hi guys. I have resently noticed that when I reach speeds of 70mph and or slightly above my car starts to vibrate . This stops when I reduce the speed to about 68mph. I think it all started when I had my first rear off side slow puncture. I have had the front tyres rebalanced at local kwik fit but the problem still persits. The car has also started to loose the 'umph' at low speed where before you could feel the car ready to go... Wonder what is wrong..... the car is a 99 1.8 20v passat APT engine at 72000miles. oil change service and brake fluid change done about 2 months ago.

Thanks.