2002 Ford Explorer jerking on acceleration

We have a 2002 Ford Explorer, 4x4 with 130,000 miles. The problem we have is when we accelerate from a stop, it starts to rapid jerking, like it is missing. It comes out of that after it is done shifting. It does this after the vehicle is warmed up. It does not do it in neutral or park, even when you speed up the RPM’s. It does not do it driving road speed of 60 or more. This just started about 2 months ago, all of a sudden. We had it checked by a mechanic and they were unable to determine what was causing it.

Assuming all normal maintenance has been performed l.e. Tune ups, air filter, fuel filter, you might try a good quality fuel system cleaner and use a TopTier rated gas.