I did buy just the IAC. Per shop the leak they were chasing down was localized around it somewhere.
So the IAC arrived today, I installed it tonight. Truck fired right up, idled without assistance (it was about 30f outside where parked and working), no CEL. Left it idling while I put tools away. Truck warmed up to operating temp, idle stayed about 1,500 rpm. Drove it around block, never got over 35mph, did rev it up to about 4,000 while driving. Ran fine, pulled good, no CEL during drive. Idle never dropped below 1,500. Parked in driveway, still high idle. Turned off. Restarted a minute later, no CEL, no hard start, still high idle. Will take to work again tomorrow if it starts in the morning, temp should be in low mid 20's. See if it comes under own power, or if the tow truck brings it back again. Wish me luck, and any ideas on the high idle? I'll check if maybe I somehow extra tightened the throttle cable during all these removals and such.