1993 Dodge Caravan limp mode

My 93 carvan witch is used as a work van ran great shifted great then it went into limp mode still runs great but stuck in second gear I was able to turn off and on to reset it and get it to shift for a little while but when that stopped workin I took it to dodge they put in new computer then the van worked great for 2 weeks then again back into limp took back to dodge they said it had a bad tranny but I think they are full of it lol so I take some where else they say it a electric prob they say there is three grounding circuits in the ranny loop and none of them are grounding so I chiecked for a ground strap there is a ground wire but it checked out good then I read bout a three wire splice in harnes I cleaned up the splice no go I changed input and output no go the place that said had ground problem said they want 80 an hour and could take up to 8 hours it will go to the junk yard before all that happens can anyone help me out that might know bout this thanks and it had the 4 speed w over thanks jamie