i got a 2000 mercury cougar. its making a rumbling sounds when im cruising at certain speeds. and when i go up his a 20 mph. and when i start the car is shakes the car. im thinking something in the axles, but not sure, and when i hit pot hole of speed bumps both the front a rear make a thump sound. not sure on that that. please let me know something. thanks

 

From what you said, I'd guess a bad rear motor mount.

 

no when i revv about 3 grand it rumbles, but at idle it dont. ive replaced both axles and the drive strut plus the stabilizer link bar.