Ford: o/d light in explorer, d light, trans shop

Question
I have a 2000 Explorer 6 cyl. At around 30-35 MPH the rpm's surge (act's like it's slipping) and then seems to work fine. I took it to a trans shop and they have 2 more like it and no idea whats wrong. The O/D light doesn't always come on but when it does the trans seems to be slugish until I turn it off and back on. Turning it off resets the light for a short while. pulling the negitive battery connector for 10 minutes resets the light for days, but the problem is still there. Any Ideas???
thanks,
gary

Answer
Gary inside your trans you have a sensor witch is called a (TR)turbine sensor it is not the speed sensor have this ck and see if it is reading RPM's.more then likley this is your problem.and you probley need to do a trans flush not a pan filter change and make sure you use marcon 5 and friction modifyer