The IAC could be gunk'ed up. Wouldn't hurt to pull it out and make sure everything is clean inside and out (including TBI where it's screwed in at). There is a way to reset the IAC, but you'll have to do a search here to find it. Blue smoke is almost always valve stem seals, but that is the first indication it's time for a rebuild IMO (if over 100k). I bought a short block from Chevy and did the roller cam conversion (it was already drilled and tapped for the spider and cam plate)... Had the heads redone with springs and screw in rocker studs. Went with CompCams for everything (lifter, roller cam, roller rockers, springs), and added a Cloyes double roller timing change set. All in was about 2k in 2004. In hindsight, I would have preferred to rebuild the original engine, but was under a time limit, and machine shop would have taken longer compared to what I did. Now, I would buy the Chevy performance 383 short block, and just throw it into the truck.