My Ford Explorer (1994) Transmission When Going From First To Secon Automatic,,,,does Not Shift Unless You Let Off The Gas And Then Put Foot Back On The Gas

My 1994 Ford Explorer Transmission Will Not Shift From First To Secon Unless You Let Off The Gas And Then Apply Gas Again,,,,,,HOW DO YOU GET TO THE SPEED GOVENOR ON THE TRANSMISSION

Could be the speed governer sticking in the back of the transmission, or a bad modulator valve