While driving along the ride is resonably smooth but when i reach around 50mph the whole car starts to vibrate (not just through the wheel) and gets worse the faster i go. if i back off the throttle the vibration disappears until i re-apply it. This makes me think its an engine issue when put under a certain load. Plugs, HT leads, fuel filter and inlet gasket replaced only a few months ago and the coil pack replaced about 1-1 1/2 years ago.
Any thoughts on the problem would be appriciated