Hopefully some of you intelligent souls can help me figure this out.
I have a 99 Cherokee 6cyl auto trans. What its doing is if you drive around town or on the fwy everything is good. However when its off the road and I start hitting some washboard or small potholes the check engine light flashes on and off quickly and the motor tries to die but usually keeps running. Now the other issue is when in low range and I shift from park to reverse the C/E light comes on and it dies immediately. If it is in high range it will do the same thing if I try to gas it. Also when I'm in low range and going down a hill and using the engine to brake it will die then too. It starts right back up but always dies again under the above conditions. The error code is PO740 which is the torque convertor. I've been reading around and haven't really seen anyone with the same symptoms. I hope someone here has had a similar problem and possibly and answer. Thanks guys!

 

I should just butt out and let someone who knows your 99 help, but! Take a minute and see that the engine to bell-housing bolts are not loose/missing.

Also power brake it a little in reverse with the hood up and see how much the engine moves. Maybe bad engine mounts and wires grounding somewhere when it moves. You might also just go all around with it idleing, shaking and jiggling any wires you can find, from the front 02 sensor, (s?) to the rear one, find where the wire is grounding. Btw, last week a guy found his, turned out to be up over the gas tank! (his was blowing a crucial fuse)