Idle rises / surges when warming up

[jfryjfry]

I searched but couldn't find anything that sounded like what I have.

I don't drive the truck too often, maybe once or twice a week.

Two times ago, i started it up and was letting it idle while I loaded stuff up. It started up and idled normally at about 700 rpm, but after about 2 or 3 minutes, the rpm rose to just under 1000 and stayed there. it's never done that before. i blipped the throttle and it went down. it stayed there for another minute or so and then went back up. i blipped, it dropped and i took off shortly after and there was no recurrence.

the next time i drove it there was no issue, but i don't remember how long i let it idle.

last time, same thing happened as the first.

it hasn't been that cold. maybe a little colder than normal (50ish), but the first time it happened it was normal.

truck is an 05, bone stock.

i have a standard code reader from autozoo, and haven't pulled codes yet, but not sure if it will reveal anything.


UPDATE: well, yesterday afternoon it was about 65ish, and i started it up like normal, but after about 30 secs, it creeped up just a little to maybe 800 and the blipping dropped it down. i read about a cold idle, but this doesn't sound like it. the only other thing i've read that involves anything similar is the icp. thoughts?????
thanks!

Jeremy in socal.