1990 4.0, transmission "hunts"

[dickboren]

Once I get to driving speed (could be 45 on a city street or 65 on the freeway), my transmission starts to hunt, in that it will keep shifting up and down. At first I thought it might be slipping, but after driving it awhile I think it might actually be in one of the many sensors that send data to the transmission.

Any ideas on where I should start?

Note I have the probelm where it takes many cranks on the starter to start, the vehicle and I read the thread that suggested the crankcase postion switch might be faulty. Could that also affect trasmission gear selection?

Thanks - DB

[Saudade]

My '88 did the same thing (both of them). I had changed a faulty CPS (crank position sensor) due to other symptoms (won't start when hot) and it didn't help the shifting although it fixed my starting problem. I later replaced the TPS (throttle position sensor) and that helped a lot. It still "wanders" a bit but I'm told that due to the torque converter attempting to lock up and doesn't quite get there. Mine ONLY happens at around 45mph.

My 88 still takes many cranks to get started when cold. Seems to be the nature of the beast.

www.autozone.com has some online service info which includes testing the various sensors. I've bookmarks the links but they only take me to the home page now. I guess AZ made some site changes.

[[Fe]weapon]

I cant tell you if there is a problem causing the tranny to search other than the speed you drive is the sweet spot where its trying to lock up as saudade mentioned
but I can tell you if you want to save the trans then dont let it do that
if it does it for too long you will toast the trans
if its constantly searching then change your speed or shift down to 3rd
your mileage will go down on the trip but you will save your trans

[dickboren]

Just as I was getting ready to start replacing sensors, the problem went away... go figure.