Downshifting at highway speeds

I have a '96 Cherokee Counry (4.0 I6, Automatic Trans. 4X4) with 69,000 miles and have noticed that last couple of weeks (about once a week) that when driving at highway speeds my Jeep sometimes downshifts into 3rd gear for no apparent reason. This has been happening in overdrive. That said, I've noticed some play in the throttle that's been happening. It just seems like there is an abrupt punch of the throttle when needed to drive up light hills, etc. I live in S.E. MI so I don't have much downshifting to do with the driving over hills or mountains, they are just light grade overpasses and things like that.

When this happens I can stop the Jeep and shut it down, restart and the vehicle will go into overdrive after that. It's as if the controls to the A.T. just need to think again about what they are doing. I'm thinking it could be my TPS. Does anyone else support that possibility? Other suggestions? Please advise.

TPS might be the issue, but I'd also suspect the CPS. My 00 shifted gears like that on the highway, and even went back and forth 4-3-4-3 before I replaced the Crankshaft Position Sensor.

Are you getting any other indications?

TPS might be the issue, but I'd also suspect the CPS. My 00 shifted gears like that on the highway, and even went back and forth 4-3-4-3 before I replaced the Crankshaft Position Sensor.

Are you getting any other indications?

Thanks for the info. What exactly determines if the culprit could be a TPS or CPS? I do not know???

One thing to add, I recently had a service bulletin where I took the Jeep into the dealership for a free PCM reflash and catalytic converter inspection (they replaced it for free so that was good:)) It is emissions recall E22 . Could the reprogramming cause an issue. I know that the PCM controls the tranny decisions but I thought that could be a possibility. Has anyone else with this reflash experienced issues? I have had the downshifts before the reflash prior to the reflash but I am noticing it now more because this is my main vehicle to drive (I totaled my car about a month ago).

My main thing is how the vehicle just does not seem to be controlling the throttle during cruise control as well as it did. The control seems to be more abrupt and the throttle does not feather as well...but then again it is a Jeep.

Are you getting any codes...as in have you tried the on-off-on-off-on within 5 seconds? That's how I found out it was my cps, I got the code.

Not sure if your year has the same diagnostics, but if not you can take it to Autozone and they'll put the reader on it for you.

I have not run the self-diagnostic yet. I am going to do that during lunch. I will figure that out. I will let you know what I figure out.

OK, post up the codes if any....

I tried the test and receive no fault codes. My "check engine" light is not on.

Isn't the test where you are key on (not started), key off, key on, key off, key on (and keep in the on - not started position), correct? Please advise on anything else.

-Thanks

Yup, on-off-on-off-on in 5 seconds, and at the very least you will get "55" (no more codes) or "done" if you did it right. If you didn't get anything at all, take it to have them look at it with the scan tool.

I retried the self diagnostic and received code 12. I figured that only means that the battery or PCM was disconnected within the last 50 starts, however, the PCM reflash happened way more than 50 starts ago. Any idea? When you say go to get it scanned do you mean to go to AutoZone or somewhere like that?

I guess ol' fred got busy, so I think that he did mean for you to take it either to AutoZone, Advance, or somewhere equivilant in your area. These stores generally do the check free of charge as part of their customer service routine. Good luck, and post back with your results.

You're probably not going to get any codes if you dont have a check engine light.
Its hard to tell from your description but Im thinking its a power problem and not a transmision or sensor problem. You have to "punch" the thottle pedal to get enough power, this causes the transmission to shift out of OD.
Does it drive like you are pulling a trailer or like its loaded with four people?
Lots of causes for this, clogged Fuel filter or cat converter or air filter.
A clogged fuel filter would explain why it runs better after sitting and restarting it.

Update:
I went to Murray's and they could not get a fault code (light wasn't on). I did the self-diagnostic and the code was 12 (followed by 55). I looked that up and that just is that the power had been disconnected in the last 50 starts (which I don't think is right).

I am good at the maintenance. I have a good air filter (< 10k miles), fuel filter (about 1.5 years old if that). I talked to a small autor repair shop and they said to call a tranny shop they know to talk about. The cats brand new due to the PCM reflash and cat. convtr. replacement.

To clarify, it just seems like the throttle doesn't seem to feather as well while driving...maybe it's me just trying to pin-point the problem on something. Any other ideas are appreciate...thx.