whenever the engine is cold and i start it up i get a small vibration in the front and i can feel/hear the engine noise get higher, then lower, if that makes sense. it's barely noticeable to a stranger, but i know my jeep and it doesn't sound normal. when driving it's fine, just when i start it in the morning, or if its been sitting for hours.

i had an s-10 truck once and it did the same thing, only a lot worse and it would stall. also the oil pressure would change significantly.

forgot to mention its a 2001 WJ 4x4 with the 4.0L