Guys, i know some of you have gotten (or will get) into a situation where time dictates that you just buy a new UIM from the jobber.
I received four junkyard UIMs from Boosty yesterday and get a chance to take a look at them closely today. Two had failed; two hadn't.
I noticed that BOTH UIMs that had failed had the coolant passages into the throttle body section occluded about 50% by plastic casting flash. The UIMs that were intact had very little casting flash in the passages.
I know that this is only a sample of four, but it occurs to me that if you're going to do a stock replacement, it'* worthwhile to inspect the coolant passages for casting flash, and if there'* a lot, run a 3/8" drill bit through the passage to remove it.
I'm going to start keeping track of this as additional UIMs come in for sleeving. May be nothing, but on the other hand, intuitively, it could be the problem, eh?