In July 2002, I purchased a 2002 Ford Explorer 4x4 E.B. 4.6 V8 AT with towing package. Ever since it was new (now with 63k miles), it's had an occasional "jerk" or "bucking" when accelerating (light, moderate and full throttle). When it is happening, it usually does it several times over a 5 second interval (but it is not cyclical or harmonic). This "jerking" only occurs in 2nd and 3rd gear and it does not matter if in over or not. I also noticed that the jerking does not occur in 4x4 high.... it only occurs in 4x4 auto. It also does not matter if the road is wet or dry. The ways people driving with me have described this problem is: 2 micro jerks per second from 20 to 5o mph Feels like a miss in the engine Feels like trans trying to shift then stopping I've had the vehicle to my Ford dealer 6-8 times (I've lost count) and they have not found anything wrong - no error codes, etc. They even installed a "flight recorder" to try to capture what is going on and still have not found anything. In fact my vehicle is at the dealership now and has been there for the past two weeks. The "jerking" is in the drivetrain and is intermittent, sometimes the jerking is there and other times it is not. I have encouraged the service writer and mechanic to drive my car home or even drive it for a weekend. They have felt the jerking but just cannot determine what is causing this, they are all scraching their heads. I've had several 4-wheel-drive vehicles and this, definitely, is NOT normal. Any suggestions on what may be the problem and how I can get this fixed?... I know somebody out there must know how to fix this damned thing. I figure it is something in the motor, a faulty sensor, internal tranny problems, faulty control trac? HELP!