Started truck up last Saturday morning when it was 9 above ,not plugged in and truck went straight to high idle. Oil pressure gauge went to 90lbs.(Auto Meter Mechanical). Can this be changed, when plugged in truck (cold start) will idle at regular but after a few minutes it will go to high idle.

 

that is normal. my oil pressure goes up to 70 PSI, but that is from low 30* to 40*. the high idle is from the IAT being below a certain temp, whatever that may be. so your truck is running normal and if you press on the brakes then the high idle should turn off. once the truck is warmed up, the oil pressure should drop to around 24 PSI at idle.

 

agreed - mine does the same with no heater - touching pedals will knock it down momentarily but it'll bump back up after a minute or so if it's still sitting

 

If you want to control this a little more, theres no way to get rid of the automatic high idle with a standard program but you could always go to the dealer and have them turn on the manual high idle. Just turn on cruise, hit set, and it goes to 1100 rpm, then the accel decel will raise and lower between 1100-1500 rpm. My dealer did this one for free