Thunking during startup and idle

Sometime its there, sometimes its not. I have replaced both motor mounts and the tranny mount and that fixed other problems, but it still have this clunking/rattling. I currently have inspection plate off the front of the tranny and i checked the 4 bolts holding the flexplate on and they are all tight. I didnt see any cracks at all. Are there any other possibilities? Sometimes its sort of a "rattling sound" like something is being thrown around down there. Are there supposed to be washers on the bolts holding the flex plate on? Any suggestions of what to check while i have the cover off, or what else it might be? Thanks. I want to try and fix this so i can get to hollister on sat....or i might wheel it as is. Hasnt effected anything...yet...


-Will

EDIT:
1993 cherokee
AW-4 tranny-auto
np231-aa sye

noone has any ideas of what to check???

check your cat. mine was clunking around a while ago and i couldnt figure out what the heck it was. then one day i had to remove my muffler and platinum started falling out of my pipe :greensmok

The exhaust pipe on the leafs? Loose starter? I took the brace off of the bellhousing to cross over pipe and mine would thunk some on start up and idle. Never did figure out exactly why though. Wifes does that now (thunks and rattles) like mentioned, it´s the CAT.