Aside from the obvious Trans/Clutch issues:

The 2.6 is prone to tossing headgaskets, especially if overheated, which is pretty easy to do if the rad's still the original. Check for oil in the rad, blue exaust, & compresion test. The cooling fan clutch may be on its last legs as well.
Beware the engine overheat....

Good luck.

Don `87 Mitsu 2dr, Rubicon survivor, GModified.