it's done this every time i've started it cold since i bought it (1 week).

when i start it, it takes about 5 seconds after i start it to go into the "high idle". it'll do that for 10 seconds or so as expected, then settle back down and i drive off.

what would cause the first 5 seconds or so of "normal idle"? shouldn't it go straight to high?

Well, the EEC’s first reaction to exiting "cranking strategy" and entering "cold idle strategy" is to keep the idle air bypass valve open 100%. You should see ~1200 rpm, then after a few seconds ~1000 rpm and from there the warmer the motor gets as seen by the ETC the lower the RPM will be untill base idle is met.

If there is a delayed reaction in the high RPM that should instantly take place during "cold idle" then I would suspect that there is a problem with the IAC or possibly a bunch of crud in the TB near the IAC ports. The only things at work are the throttle body, the IAC and the computer and wiring between the IAC and the computer.

One of the first things I always to do an older truck when I first get it is take the throttle body off and clean it out real good.

andym said:

One of the first things I always to do an older truck when I first get it is take the throttle body off and clean it out real good.

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i'll give that a shot - i also want to give it some seafoam through the brake booster line...couldn't hurt