Have a stock 92 D250 (2WD) Cumins. Trans upshifts fine but does not want to downshift out of 4th gear if I am slowing down and then reaccelerating. So if I'm driving 50 m.p.h. and slow down to 15 and then accelerate trans stays in overdrive and my acceleration is non-existant. If I manually downshift to 2nd gear it accelerates great and then I tap it into 3rd gear at about 30m.p.h. and it upshifts into 4th gear around 40 m.p.h. Anyone else have this issue? What did you do to fix it? (yeah, besides ripping the trans out and converting it to a manual.) Would a shift-kit fix this or is it a visit to a transmission shop?
Thanks

almost sounds like a sticking governor, or something in the valvebody acting up, but i'm no transmission expert by any stretch of the imagination.
consider this as a bump in the hopes that someone like Cope or other transmission expert sees this and can give the correct diagnosis and cure.
as to shift kits, i have installed them in every transmission i use, including front wheel drive transmissions[transaxles] starting way back in the mid 1970's.
they seem to work out for me doing so, but i like shifts to be crisp and be able to feel them. not bang/screech hard in every instance, but i really dislike the "slide into gear" shifts of some transmissions.
just my personal preference and experiences over the many, many years i have installed shift kits.
your mileage will vary.

Overdrive on these is electric controlled. But by 15 mph, you should be downshifted to 2nd I would think which would knock Overdrive out hydraulically.

For fluid to engage overdrive, the trans gas to hit 3rd gear. Overdrive gets it's oil feed from 3rd..

So, some questions.

Speedometer working?

Cruise working?

If you press the button on the dash, dies it prevent overdrive from engaging?

Is there some delay between 3rd and 4th?

I'm wondering if the shift solenoid is stuck or wiring might be grounded.

Does the speedo work? As mentioned the pcm should kick the od off at lower speeds.

When it doesn't drop out of OD and the acceleration is sluggish, have you tried more throttle?

Thanks for the input:
!. Yes, speedometer is fully functional.
2. Overdrive lockout switch on dash does not lock the trans out of overdrive.
3. When I reaccelerate from a slow speed I can depress the throttle completely and the performance is terrible.
4. If I am driving fast enough to engage overdrive, but come to a COMPLETE stop, trans will correctly downshift and I will start off from a dead stop in 1st gear.
5. I almost never use teh cruise but to the best of my memory it does work.
I have over the several years of ownership, changed the overdrive solenoid 3 times as the replacement parts now available are not as reliable as the oem parts.

Something is not right there. I would test to see if the pcm is cutting the ground to the od at slow or stop. Another thing is the TV(throttle valve) adjustment, If it's off it will effect od/shift. Not sure if they are the same for the diesels but something you may want to look at.

Here's what the book says: