I've had similar issues as well. When i first bought the truck(93 lightning 351 w/e40d) it would shift hard but shortly after it just stays in first gear, the only way it shifts if you give it some gas. Speedo jumps sportadically at 55+mph(speedo worked fine, only replaced VSS for a troubleshooting step for the transmission). Here 's a list of what i've done.
Replaced:
VSS(twice)
TPS
New PCM Relay
Replaced all fuses
Neutral safety switch(twice)
PSOM.(went back to orginal after no change)
shift soleinod
+
Transmission fluid/filter change(no metal shavings found)
replaced springs accumaltor body
The wierd thing is that it would shift fine after a hard reset and then go right back to delayed shifting.I'm down to either a bad PCM or the clutches/bands are worn out in the tranny. Please help.
