I have the 1994 3.9L, 42RH transmission.
I have determined the performance issue is a bad torque converter per the FSM.
When I search for torque converters I end up with choices for lock up and non lock up. I am fairly sure which is why I want to know for sure how to tell which TC I am supposed to replace the OE one with.

 

May not be much help, but i know for a fact that my '93 3.9L uses a lock-up TC.

 

Thanks OMGnanerpus. I think that is what I have but I am unsure and do not know yet how to know on my own.
I have the 95 FSM PDF from the FAQ page but it is explicit that the 95 42RH tranny is different from the previous years. While a lot of it applies I don't know enough to know what I don't know.
Has anyone downloaded that PDF of the 46RH - 42RH transmission service manual? The linked page wants me to join google to download it. The FSM didn't.

 

I spoke to more tranny people did an experiemnt and finally had it in to the mechanic to "Check if the motor is running right" resisting all entreaties to provide more info. They checked it over the motor is good two codes both tranny having to do with torque converter. The mechanic said it is slipping, this must be what I was calling jumping. The transmission shop I took it to said the codes, 37-45 essentially say it is slipping. The guy drove it and said it wasn't so much slipping as it felt like it was losing pressure. There are two reasons bad inner seals or bad pump both get fixed with a rebuild.