I have a 98 Cherokee 4.0 4x4 automatic trans with overdrive. and the check engine light is on. I did a scan and the code I received is P0740 (torque converter clutch no rpm drop at lockup) took jeep out on highway and everytime it shifted i could feel and here the rpm's drop did this several times. Anyone have an idea what could cause this code

 

The converter locks up in O/D- Look for the RPM to drop in top gear. You didn't state how many miles your Jeep has. It could be either the computer not commanding the converter to lock up, or the converter has internal damage, would be my guess. I'm not even positive if Jeep has an electronic style converter or not. (most are mechanical/inerita type) Maybe changing the ATF multiple times will help? I'm not sure on the Jeep autos, but older Fords had a drain plug on the converter itself.

If you had access to a shop- they would have a PC diagnostic software of some sort. Snap-On Shop Key, Mitchell On-Demand, or Alldata (aka NO data). If you had the ability to access this, it would give you a troubleshooting tree to follow. This is the easist way to diagnose CEL problems.