92 voyager tranny stuck in low gear

Help! On a 92 Grand Voyager with a 3.0 motor I recently swapped out the 3 speed automatic with a low mileage junkyard unit. When I went on test drive it was stuck in low gear. Flushed radiator tank and tranmission and installed new filter. Adjusted the kickdown linkage and still stuck in low. Took to local trans shop and they pulled and flushed out the valve body and set some govenor pressure. Tranny was fine for a week the suddenly back to stuck in low again. Took home and flushed trans again and replaced the valve body with one from original trans (never had a shifting problem with old tranny ) Bench flushed the valve body before replacing. Check all gang plugs in engine bay and checked all grounds. Only 3 electrical connections on trans and all seem to be working well. No codes set. Where to go from here? My Alldata and Mitchell's On Demand don't seem to address this type of problem.

No one has an idea?

Since you posted late maybe you'll get some help as folks come home from work today. All I can say is since trannys aren't high on my experience list it might be time to decide which tranny to tear down and rebuild, the original or the junkyard gem.

Thanks for the response RIP. Ya the whole idea was to NOT rebuild one and get this guy back on the road quick ....LOL. Was hoping some member was a tranny guy and had seen this a million times already (and maybe a quick fix for it ). I too am not a tranny man and this guy is into this tranny for more than I would give him for the van...LOL

Ya I can understand that. If you don't get any responses you could try browsing through the forum and send a private message to whoever sounds like they might know trannys. I know there's a few out there but, cant recall their forum names. Cheers!

If it's a A413 3 speed, see:
http://www.allpar.com/eek/autox.html

If it's a 4 speed A604/41TE, see:
http://www.allpar.com/fix/trans.html

3 speed: Check for the kickdown rod return spring problem mentioned on the first web page. If that's ok, try a bottle of Lubegard Red. It does help sticking valves. If that doesn't work the governor may be stuck/worn out. Or the front band may be fried.

Thanks Rawtorque, I was looking for allpar last night and couldnt find the trans section.To night a search brings up lots of pages but they wont let you see anything but the first page ...just my luck...LOL

When I had it apart changing the valve body I looked at everything that moved and nothing seemed stuck. Someone mentioned the shift control module and a speed sensor. Got any ideas about those?

thanks

I want to pull the govoner and flush it out as recommended by one source but I dont see where it is (suppose to be evident with vb out of the way ).
does anyone have a picture from a manual or something to go by