1999 Chrysler Town & Country 3.8L Eng Limited p0604 p0605 p0700
Re-manufactured transmission, runs great! After it warms up it begins shifting hard and eventually it ends up in limp mode (2nd gear)
I don't think it's mechanical because of how well it drives at first. could it be a coolant issue, or electrical?

 

Both the 604 and 605 are flagging memory problems in the powertrain control module (PCM). 90% chance the PCM is bad but it could be something external to the module. The 700 is telling you the transmission control module (TCM) has detected a fault in the electronic transmission control system. Could be any number of culprits. To get a better idea you'll have to connect a scanner capable of reading TCM codes. Night try resetting the codes with a scanner or just disconnect the negative battery cable for a few minutes, then see which codes come back and when.




https://www.obd-codes.com/p0604
https://www.obd-codes.com/p0605
https://www.obd-codes.com/p0700