I think Whitey's Battery is going...

[ecomodded]

With my tdi's high idle start up it was due to a near unnoticeable tarnish over the battery terminals.
The alternator belt would squeal after starting as the alternator sucked the life out of the motor to charge the battery.
Cleaned the terminals put a new battery in and the alternator belt has not squealed since.
A fully charged battery in my car makes it run like a top, a weak battery makes it take off like a slug, car is really voltage sensitive or the alternator is sucking the life out of the motor.

* But *

You may have a bad battery and something else wrong, the air conditioning increases the idle when activated for instance, or the voltage regulator is causing issues, You should be able to determine the problem with a multimeter. Since it hasn't thrown a code, it may be charge related.

[nemo]

Just do a internet search on your truck and engine, see what results you get. Specifically look at the result from forums that match your vehicle.
The first thing I would be looking for is a vacuum leak and it won't throw a code unless the ECM ( electronic control module) can't adjust the fuel trim enough to keep the air to fuel ratio correct. Had that experience before and like your truck it would idle high at start up and improve after warm up. Hope you get to the bottom of it quickly. Post what you find, I'd like to know.

[MPGranger]

Well, the battery was at 12.2 volts from my scangauge2, then I cranked it and it went to 13.6 for the bulk of the trip. It also dropped down to 11.something right before I cranked.

I was thinking it was the battery because it happened the first morning after installing my new ultragauge em and read about the battery drain issue. This is the inciting moment. Changing the scangauge to ultragauge is the only variable that I can think of.

So what should I look for for high idle issues?

Would a motorcycle tricklecharger work on my truck's battery?
Can I use some coke to clean the connectors?

[ecomodded]

First off replace the battery because some cars will up the idle to charge a depleted battery.

I use a battery tender junior for all my batteries.
I have permanent connectors on the jetski and the car.
the junior is only .750 amp and works very well.
2 amps is plenty but the 3/4 of a amp worked for all my past vehicles batteries fine, a overnight + affair.
I would suggest the full size Battery Tender, 2 amps is more reasonable, my battery tender junior came free with a motorcycle a few years back. I also have a full size 10 amp 3 stage charger i use for real charging not just topping up.

Broken sensors can cause a high idle, you should read , on the engine control sensors and modules, often they will explain what a bad sensor will cause and how to check.

I am curious how the scanquageII could drain off a battery, something small and simple (circuit board/display) like that should not be a major drain.
Off hand i would assume 0.050 amp at rest ( it may not be).
Possible it is keeping the cars computer awake or some such thing , i don't think it could be seriously effecting a battery in even a week of sitting, but i have no first hand experience, unlike some users..

[MPGranger]

scangauge didn't cause the drain, Ultragauge did and there is a section in the owners manual about it.
So clean the connectors and trickle charge the battery.
And then do some research...

Thanks guys