I've noticed as of late that when I let off the gas at highway speeds I feel this pulsation/rumble/ in the gas pedal only. I can't say I've noticed it at lower speeds. When I feel it, it's that moment right before you let off the gas entirely to coast-if you hold it there it will continue to do it. Furthermore, if you hold it there I get a funky smell that almost smells like burning, but it's hard to say. As soon as you re-accelerate or get on the brakes, it's gone. It's almost like something is "getting stuck" and gets freed up once you brake, or accelerate. Could anyone shed some light, please?

 

Seeping valve cover gasket? Dry U-Joint? What has the maintenance history on the vehicle been? When was the last time you checked ALL of your fluids, diffs, x-case, power steering, etc?