Whats the problem?????

I was driving my XJ down the street the other day and I noticed something that is really bothering me. I was going about 15 miles per hour when I noticed that my jeep was constantly speeding up a little and then slowing down. The engine RPM was constant and I didint hear anything strange in the motor while it was doing it. The funny thing was when it slowed back down, there was a strange clicking sound every time from under the body/engine area.

Is this a sign that my trans is going or is there another problem that I dont know about? My XJ is heavily modified and has 93K miles. Any help would be great.

Sounds like it is time to replace the tranny filter.

You think the filter alone would cause something like that?

Does it do this at an idle? My XJ did this when it had a vacuum leak- in my case the bolts for the intake manifold had worked loose after installing the exhaust header

I didnt check it at idle, but I will now. I didnt check and see if the headers were cracked either, they are stock and I heard are prone to cracking.