I did a search and didn't see any other thread... but my 99 sport idles rough while in gear and stopped.. now when i say idles rough..the motor seems to run fine... but the whole jeep starts to humm and vibrate almost like someone had a subwoofer and they are parked next to me.. as soon as i take off it goes away.. and as soon i put it in park or neutral it calms down 99% I've replaced numerous parts/sensors to no avail... I've tightened everything thinking it may be a motor mount or something of that nature and nothing has fixed it.. its not a consistent occurrence but it does this more often than not and it's getting awfully annoying.. has anyone else had anything that aounds similar to this?? Thanks!

Ever cleaned your throttle body? Start with that.

http://cruiser54.com/?p=60

Do what it says in the link.

Compression

WHAT?????