Bottom end freshen up

Hello,
I have an 88 XJ 4.0l, 4x4, automatic 205 thousand miles. Just recently started to develope what I think is bottom end chatter. Only makes noise when warm and at idle both in and out of gear. Sounds like it goes away with RPM increase. It is not your typical loud rod knock yet anyways.

Uses no fluids, burns no oil, and all of cruisers renix tricks have been completed. All sensors either new or cleaned and have been tested and adjusted.

Wondering what you guys think. Freshen up the bottom end, complete rebuild, or could this be something else.

Thanks

Oil pressure when it makes the noise?

20psi on mechanical gauge, compression is good across all cylinders, did a leak down test in all cylinders they were good, no exhaust or intake leaks, vacuum good and no exhaust restriction per vacuum test.

Only reason I am asking is I don't want to do something for nothing only to have to do it over again. I just retired from the military and have till January to fix it when I start college. Right now just part time jobbing it so have other means of transportation (my Harley) and time.

I would inspect the flex plate first. I wouldn't hurt to pull the pan and take a gander at the rod and main bearings. You might get away with just a new set of bearings.

I think I would take the time to probe with a stethoscope, before tearing into the bottom end.

Its usually never a good idea to just freshen up the bottom end or for that matter the top either because once done it doesn't take much time for the other end to start giving you troubles. Any weak/worn or marginal parts or machine work show up quickly, so might as well do a complete overhaul if it is required.

Try this first:


http://www.cherokeeforum.com/f51/how-fix-flexplate-knocking-125547/

Flexplate was good. I believe it has something to do with the transmission. Now intermittently when stopping at a stop light/sign it feels like the torque converter is staying locked, if you let off the brake move forward a bit it it feels like it unlocks and everything is normal.