High RPM's at highway Speeds.

It's a 1990 Jeep Cherokee Aw4 4x4. I just replaced the iac and all vacuum lines are new. Problem with my Jeep is that around 45-55 rpm's it just sits around 2 grand and when you want to speed up it has to goto 2500 to even move. Now my Jeep has never hit 3000 rpm's without being in neutral. You can floor it from a stop and it will always shift at the same rpm's as if you were driving normal. I tried the other day to shift it manually to see if I could hit 3000 rpm's and it got up there almost and it acted like it popped out of gear and reved up real high. I do have an exhaust manifold gasket leak and it is running rich. Just really need help on this I'm stumped.

You said you shifted manually--with the TCU unplugged?

Unplug the TCU, drive shifting manually. You should have 1st in 1-2; 3rd in 3; 4th in D; reverse, neutral and park. You will have no OD or torque converter lockup. If you get these results, then your problem is electrical in nature, not mechanical or hydraulic.

First, always check the quantity and quality of the trans fluid--red, doesn't smell burnt, near the "FULL" mark?

Second, adjust the throttle pressure cable.

Third, test (and on the Renix adjust) the TPS.

Fourth, unplug the TCU and try shifting manually.

Ok, when you've done all that, if you are still having issues or need further assistance with testing, post up.

AW4 article: http://www.transonline.com/transdigest/magazines/1997-10/Shift Pointers/index.html

Renix sensor article: http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

Good luck.