1998 Durango O/D off and Trans Temp light

234K miles, 5.2L 4X4 Governor sensor replaced and fluid/filter service ~8months ago

This is my soon to be mother-in-law's vehicle and has started acting up recently. I've looked for similar posts and have come up with little on this issue that mentioned a clogged check valve in the return line from the cooler. Have not had a chance to look for it nor do I know of a way to check it without removing. Thanks in advance for your help.

When driving to and from town, ~20 miles after letting it warm up for a few minutes the O/D will switch off and the Trans Temp light will come on briefly before going back to normal. The first time it did it was about a month ago and happened once then with increasing frequency about a week later. Fluid does not look or smell burned and I don't know much about transmissions. Last night on her way home it did this three times and did not correct itself without her stopping or shifting to neutral. Short of taking it to a shop I am lost. Any ideas on what may the cause of this issue and ways to resolve it would be greatly appreciated?

Ben

weak, failing pump? Bent/damaged clogged lines? Clogged Trans cooler?

weak, failing pump? Bent/damaged clogged lines? Clogged Trans cooler?
So have the shop test the pressure and flow or is there a way to do so with some basic tools?

98 5.2 4x4 factory tow package, 103 k. This will be fourth rebuild in 14 months and 3400 miles, by the second tranny shop. No one can figure it out. It starts to grind then it won't move,no trans temp light would come on. This last time it was on first lengthy trip in years, 110 miles. Kicked out of od,trans temp light came on turning on to my street.pulled in driveway, put into neutral to cool it down. Shifted into reverse after about ten minutes and light going out, loud clunk and reverse is gone. Fluid is like new not burnt at all. Trans cooler has been replaced at last rebuild, radiator bypassed and drain back valve in line removed. Its on its way back to shop on Monday, will let u know if they can finally figure it out. I have had this durango since 2000, it has never been neglected, no leaks perfect condition, I don't want to have to get rid of it but this is getting ridiculous.