Having an issue

Hi I'm new here and have a 2003 ford explorer. I'm a mechanic and have been a auto mechanic for years and years and now work on Tractors and trailers for FedEx freight. My explorer when hot , makes a jerking like a bad engine miss but it's not the motor or trans. And I found that if I hit the 4x4 switch when it does it ,the problem stops as soon as I push the switch and will come back if I turn it off. It doesn't do it when cold and for as long as you drive till it's warm and you stop and start again like from a stop light. Seems to be getting worse lately. Any Ideas????? Sorry for the first post being a problem.

Does this happen at idle or even when driving? What else could make a car jerk or shake if its not the engine or trans??? Could you try removing the engine and trans and see if the car still jerk? Just kidding. If you just feel the jerking when the car is hot, it could be your trans running low on fluid. I'll prefer replacing the fluid and filter rather than adding fluid.

It happens only when taking off from a stop ,nothing at idle. but like I stated if it doing it and I turn on the 4x4 switch it stops jerking instantly. Turn the 4x4 off and it starts again. And once up to speed it goes away till you stop again.

Update.....found the problem. I unplugged the Motorola transfer case controller and now the rig drives great and feels like it needs less gas to make it go. I believe the transfer case was shifting in and out of 4x4 during acceleration casing my shuddering. I'm just going to leave it un plugged for now. The 4x4 lights just flash a couple times every few miles. Tape will cover that. I really don't want to put money into this rig right now.