stuck in school zone speed

[6.0Lpowerstroker]

i have a 2003 250 6.0L and it just hit 150,xxx it starts good, and idols fine. but when i start driving, i can only go 20 mph. i live right off the highway so this is no good. i floor it and the engine roars up to 20 mph then just stays. or, if i try to sneek up to 20mph then punch past it, i still stay at 20. and i cant get going any faster. this happens even if i start the truck and let it idol 20 min before i leave. the ony way to go faster is just drive for about 10 min, then all of a sudden the truck realizes it on and starts to drive normal. we have diesels at work, and none of them have ever done this. anyone have a similar problem? or is there a fix for this? i realize it takes a sec to warm up but this is rediculous.

thanks for any input

[arcticatman]

sounds like the tranny

[Dave]

Scan it for codes. Pull data while driving it

[BDSford03]

weird. is the tow haul light flashing during this? it kinda sounds like trans might be in Limp dick mode. What are your RPMs doing when you hit 20mph?

[thesmokinstroke02]

sounds like some tranny issues

[wags1992]

Does it smoke when this is going on?

[Black&Gold]

try disconecting the batteries and then reconecting them. dont know if this will reset the comp's but its worth a try

[6.0Lpowerstroker]

ok, thanks guys. i'll take a look into the trannie. so i assume this may be related to a "shaking" or jerking at about 50-60mph? the truck will kinda vibrate if you just barely push on the gas. but goes away if you really step on it or let off. between third and fouth i think.

[6.0Lpowerstroker]

no white smoke or any kind of smoking during any of this. as far as the rpm's its roaring. about 3 to 4 grand. like i said tho, all of a sudden its just ready to race and drives like normal. i'm really puzzeled here

[Get Some]

It might be your ficm. My truck was doing the same thing right before my ficm went out.