i have a 1990 f150 5.8 with an e4od and it wont take off from a stop in drive just barely creeps but if put in man1 and upshift to man2 then to drive it moves fine. thought that forward clutch is bad and have the trans on bench with valve body off air testing and all clutches seem to be working fine. cant test coast clutch though because I cant fit air nozzle to feed and don't have a test plate. I went through the valve body and don't see anything wrong all valves are free moving without any restrictions and no broken springs. what am I missing or don't know

 

Was your oil burnt? If so, you probably have burnt clutches.

 

Clutches replaced with all piston seals and o-rings, but concern is still present

 

Had the same sort of problem with the E4OD in my 92 F-150. Took it to an individual who has some pretty sophisticated testing equipment. He checked it out and all he could say for sure that it had to be some thing electrical. Told me to pull the ECM and see if it had any burnt capacitors. Well it did. I got a replacement for it from Auto Zone. I swapped it out but it still wouldn't up shift like it was supposed to. I had already changed out the manual positioning lever switch on the side of the transmission so I knew that it more than likely wasn't it. So only thing else left was the solenoid pack. I bought a rebuilt one from O'Rielly's and got it installed. Problem solved! Transmission up-shifts just like it's supposed to. Hopefully this might be helpful to someone and save they a lot of time and trouble.

 

When those electrolytic capacitors fail, the fuel system is the first thing affected. Won't cause transmission problems like that. BTW- I would be surprised if his 1990 F150 is still on the road.