i have 94 explorer automatic 4x4. its not shifting unless i let off the gas and then give it gas. also when going up an incline it downshifts. i replace the transmission filter and that was no help. was wondering if maybe the vacuum diaphragm could be a posibility or if i have to take it to get scanned. thank you

 

Vacuum modulator (diaphragm) or bad clutch plates inside the transmission are two likely suspects. It's supposed to downshift when going up an incline if it's fairly steep. It should only shift down a gear until you reach the top of the hill and then should shift back up. If the engine isn't pulling hard to get up an incline your detent cable may just need adjusted. Bad clutch plates could causeALL the problems you just mentioned though - so if you have high miles I'd plan on a rebuild (or just some new automatic transmission clutch plates and the proper snap rings).