I have a 91 F250 with 351W and 4R70W went to move it today and it wouldnt shift past first gear. Reverse works like a charm! Its full of fluid and isnt leaking..its also been sitting since 2009. Its only been loaded on/off a trailer a few times prior to today. Not sure if it could be from sitting around or not?? Maybe fluid just has to move around more?? Any input would be greatly appreciated!

 

More likely it's an E4OD but both are completely computer controlled so look for anything obvious like disconnected wiring or dirty/corroded connector on the MLPS module on the trans and then pull the codes.

 

Yup, 4R70W did not exist until the mid 90s, and the AOD-E wasn't around until '92.

 

Sounds like a Tps issue, happened when my volts were below .8 at idle

 

Its definatly a 4R70W I verified that in the past with the dealership...Ill check the tps tomorrow..how would I go about adjusting/testing the tps?

 

Your dealership is wrong. The 4R70W did not exist in 1991. The 4R70W's precursor - the AOD-E did not exist in 1991. Ford only had two RWD 4 speed automatics for trucks in 1991. The AOD for light duty trucks, and the E4OD for 250/350. Everything else was a C6 3 speed.