Hello all.
I've been a Ranger owner for many years, but just bought my first one with the 4.0 and automatic.
This one is a 1993, and has about 130000 miles on it.
The issue I seem to be having with it is I will be driving down the road, and every time I take my foot off the accelerator, the transmission downshifts out of OD for maybe 5 seconds and then goes back into OD.
Anyone have any idea where I should look to stop the truck from doing this?
It does the same thing if I have the cruise control set, and tap the brake to shut the cruise off.
If I push the off button to the cruise, it doesn't downshift.
Any help and suggestions are greatly appreciated.
Thanks all.

 

You should have an A4LD trans in a 1993.

It still used a vacuum modulator to aid mechanical shift points.
A4LD in your year had Torque converter lock up solenoid and a 3/4 shift solenoid, these are operated by the computer, and 3/4 solenoid could be the problem but you would usually get a flashing OD light if it was an electrical/computer issue.

And usually a problem with vacuum modulator would effect 1/2, 2/3, and 3/4 shifting, not just 3/4, but it is easy to check, and free, lol.
I would remove the vacuum modulator hose and check it for leaks/cracks, also transmission fluid, modulator can leak fluid into hose which throws off vacuum level at modulator.
High vacuum happens when throttle is closed, low vacuum when throttle is open, vacuum level helps trans to "know" when to up shift or down shift