any one know where id start lookin for problems with my automatic not down shifting. dosnt do it on hills, flat ground or anything at all. i just dont know where to start lookin. it will down shift fine if i do it manually and it up shifts just fine also.

 

Try adjusting the TV cable first.

 

What about the complete opposite? Downshifts for no reason and hits overdrive alittle early for my liking...

 

Almost sounds like a converter lock up solenoid acting screwy. Is it happening at part, 1/2, 2/3, full throttle? Does it do it while cruising at a steady speed/on cruise control?

 

Don't have cruise but yes about half to 2/3 throttle...

 

Hmm... Imma gonna have to research this one a bit.

 

yeah mine seems to shift a little early in all top gears and dang is it annoying!!

 

Either one can be caused by the TPS. This gives feedback to the torque converter to lock or unlock and seems to be random but a new TPS will usually solve that issue.
Cheap87 yours will need to be adjusted as well. The Renix Jeeps (87-90) are adjustable but the later ones are just plug and play.

 

any idea how much a new TPS runs?

 

Try this paroxysym. Clicky

For the Renix years it is not as cheap. Clicky

 

they give me two part numbers... hmmm a DEM and a CRB

 

Not for automatics.

 

hail all to the renix guru, it solved my prob. took some time but its fixed. by the way why do they call it a renix model? what does it stand for???

 

http://en.wikipedia.org/wiki/Renix

 

Never read the Wiki explanation but have always been told it is a contraction of the two words Renault and Bendix. Renault and AMC had a partnership in the 70s and 80s and built the first FI computers for AMC which owned Jeep. Those were manufactured by Bendix thus the two words previously mentioned.