Fant'n....
Chrysler issued a TSB on the problem you describe. It is TSB number 21-08-94 and the repair involves installing a drainback relief valve in the transmission oil cooler pressure line.
NO: 21-08-94
GROUP: Transmission
DATE: Apr. 29, 1994
SUBJECT: Delayed Transmission Engagement/Torque Convertor Drain Back
MODELS:
1990 - 1994 (XJ) Cherokee/Wagoneer
1990 - 1994 (YJ) Wrangler
1993 - 1994 (ZJ) Grand Cherokee/Grand Wagoneer