Tell your friend the only thing it could possibly mess up is the IAC and that you'll give him a new one (revised version) if that happens. Otherwise maybe it would be faster to try someone else; maybe even mail your ECU to them (with an agreement that they'll be quick to test it and send it back) to have them try it and send it back although I'm sure you'd rather someone fairly local as would I to get it back immediately. Pump him up too; tell him he'd be contributing to a cause greater than just your car, but his and a big community. lol
Where do you get oscilloscopes? Are they expensive?
I recall at NG05 that "
Import Power" had a leak (boost I think) or similar hesitation issue and he was insanely pissed cause he'd gone over everything and that car was STRIPPED of all everyday passenger vehicle stuff... only rigged for racing. As I recall he wasn't able to resolve it while he was there, but perhaps he did later on. Maybe ask him what he did to fix his issue.
GOOD LUCK man. I'm all out of suggestions. Aside from electrical testing and logging of all results I don't know what else to tell ya. Some have sold their cars and tested just as much and more so than you even without ever fixing the problem. Sad but true.