Hi ZTH members! I really really really need you guy's help on this problem. I drive a Proton Satria Mivec 2002.
When I do my daily driving around PJ, the car is like normal. But once i hit the highway on the way to ipoh, around 1 hour and a half later, my car vibrates and gives out a sound something like "Doop Doop Doop". It feels like as if im driving over the small reflector lights on the road. AND THIS ONLY HAPPENS AFTER MORE THAN 1 HOUR.

Everytime when this happens, i stop at the...