[ImperialCrown]

If the ATF is full and fairly clean still, then I think that you will need more than a fluid change to get it out of limp-in. There is a fault code stored in the TCM that will help us determine the reason.
There were other scan tools (Snap-on, OTC, etc) that can read OBD 1 Chrysler codes. The dealer can't justify going over the base diagnostic charge just to read fault codes. Call around.
You will need a dealer for a TCM flash if one is possible. TCM's weren't flashable until 1994. Yours may not be original. Flashable TCM's are recognizable by the cooling fins on the housing. There may be an authorized software update sticker soft_label.gif on or around under the hood if the flash has been done. The latest software (4761847AA for the 3.3L equipped transaxle) was released late 1995. The new software may a huge improvement in shift quality and was less prone to faults. If you don't have the newer style, you will need one and it may have the latest flash in it.
ATF change intervals will vary by duty and conditions. It really doesn't sound like you need new fluid at this time.

 

[ImperialCrown]

Stick-shifts were very rare, even when these were brand new and only available with the 2.5L 4-cyl.
It would still be nice to know what the stored fault code is in order to know how bad the situation is. A fault code is a good starting point. (Some fault codes were 'cured' with the TCM software flash described below.) Then decide what to do.
This is the TSB for the TCM reprogramming update: http://www.robskorner.info/faqs/TSB/18-24-95.pdf