I have a 1995 Eclipse with an automatic transmission. The transmission was rebuilt and has about 5,000 miles since the rebuilt. But when I’m driving the transmission will shift down to a lower gear and won’t shift. I have to stop the car turn of the engine and start it back up. That clears the problem for a couple of days and then it happens again. I have taken it back to the transmission shop and they scan the computer but there is no trouble codes stored. They had my car for three days and drove it several times but the problem did not reoccur. Has anybody else come across this? Any help will be welcome.

Like it will shift from 3rd to 2nd and then not shift up at all? Does it do this when you go into passing gear i.e. when you are cruising and then stab the throttle to WOT? Or does it just downshift for no reason what so ever?

sounds like its going into limp mode for some reason.
but not setting a CEL into memory.

Hard to diagnose like that huh.. could be mmmmmmmmmmmmmm mmmm
clogged/kinked tranny cooler hose maybe, temperature is getting too hot and causing limp mode then once it cools down it functions correctly.

I dont know what to tell you except your going to have to catch it when the CEL is on.

mcgyvr is right, it does sound like limp mode. Leave it to the pro :)

It just downshifts for no reason and as soon as I turn off the car and turn it back on it will shift fine.