Any suggestions for problems that would result in error code P740 Aux. Emission Control in '97 Grand Cherokee?

p0740 means that the torque convertor clutch was commanded on but the rpm did not drop. possible causes are torque convertor, trans pump, input seal rings, pump seal rings, valve body, or tcc/3-4 shift solenoid. any of these are expensive. don't throw parts at it. take it to a delaer or a good trans shop.