Hi. Have some problems with my F250. Got it about a year ago and recently
got some problems. I noticed that the idle speed got very high suddenly. Also when driving it never went down to normal. Also When coldstarting, the truck had to heat up before it was possible do drive. Otherwise it just died.
Now the trans has also started to malfunction. When driving it wont shift up unless I drop the gas pedal. As soon as I accelerate it downshifts 1or 2 gears.
And now for the final, yesterday it started up, ran for a minute and died.
Wont Fire up again...this is My first "newer" truck and I have no Idea where to start..Thankful for all suggestions.

Toivo

 

You need to see what codes you have as they would be a big help it finding out for sure what is wrong with your truck.
But sounds like you may have a bad TPS and you may also have a stuck IAC valve.

TPS: Throttle Position Sensor.
IAC: Idle Air Control