last night i wast on the highway and i got on it it would climb to 70 then wouldnt accelerate past 70... the rpms went close to redline like it usually does with the pedal to the floor but would stop instead of shifting...?

also i tried with overdrive off and overdrive on did same thing regardless.

 

Clogged cat and blown plenum most likely. Do a search here on DF for both subjects.

Here is some help, https://dodgeforum.com/forum/2nd-gen...um-thread.html

 

what about a tps issue?

 

I doubt it. Check the plenum, TV cable, Gov sensor and solenoid , etc..... I'd check the plenum first and at least eliminate the most common problem first.

 

if i look in the exhaust manifold down on the bottom there is a layer of black oil or grease but its not puddled up in there or anything

 

You really should pull the TB and look around the corners of the manifold with a mirror .

 

Tighten your valve cover gasket bolts. I do mine every oil change.

 

I just noticed that the OP said "exhaust manifold". And that's obviously not right.

 

I have this exact same problem with my 94 Dodge, and the mpg went to 9. I had some mechanics tell me that it needed a new tranny, but the bottom gears are so smooth. It just won't go into overdrive. I already changed the TPS, and it seems to help the bottom gears be even smoother but no fix. I am not a mechanic, but is cleaning that plenum thing something I could even do?

 

Does the truck in question have power windows?