Whenever im hauling a heavy load like the chipper for our tree business when I get to a hill the transmission never wants to shift down so I have to manually shift to 2nd, same thing when im on flat ground if I floor it it should downshift with the load on it but it just bogs down, anything that I could do to help the transmission like a programmer? Any recommendations would be appreciated

1992 Ford F-350 Dually idi N/A 100k miles

 

hey there fatcat.i run a tree service with my idi truck too.
my truck was doing this when i first got it as well.hopefully it's as easy to fix as mine was.
remove the TPS (formally called FIPL) plug and clean it,then apply dielectric grease and put it back on.
take her out for a drive.if this doesn't do the trick,then it's likely not adjusted properly,or has failed.
advance auto has the original FORD TPS.its priced right,they offer a lifetime warranty on the thing too.
it's boxed and sold under the brand name "BDW".

this sensor is located midway on the side of the injection pump on the drivers side of it.it's a 3 prong,and is held on via two T-27 torx screws.you can't miss it.

this sensor tells the E40D's devoted computer where your foot is on the throttle and sends the required info to the trans to have it shift up/down for you to state the basics of it.yours is not working properly either due to corrosion,chafed wires at the plug,not adjusted correctly,or faulty.
i always test a sensor before replacing it after making sure the connection is clean.you can do this with a sensor tester or just a volt meter.your looking for a constant sweep with no spikes,or dips through it's entire range.
p.s. i just changed mine today.

 

Oh ok I will give that a try, thank you so much