Apologies in advance...another 0299 question

My '06 has only 28,000 miles on it. I'm the original owner. Never had any problems until recently. Back in July, I started the truck one day (after it sat for about a week) and about 30 seconds later (While still in my driveway) the CEL came on. I put on my code reader and got the infamous 0299 code. I read numerous threads on here and found various reasons. I checked the turbo boots and found the lower one to have a crack in it. I purchased new OEM boots and installed them. Cleared code. Nothing happened for several weeks. Went out one morning, started it up and up comes 0299 again. Took truck to a good friend (who's a very good mechanic) who scanned the OBD with a very expensive Snap On code reader. It showed several possible causes. I started with the EBP sensor. Installed new one, cleared code. About three weeks later, 0299 comes on again. Keep in mind the ONLY time this 0299 comes on is after I've started the truck after it sits for a few days. Doesn't come on during regular driving. Truck runs fine, turbo spools up with no issues, no symptoms AT ALL of anything wrong. Today I installed a new OEM VGT solenoid. I'm not feeling very confident that this will fix the problem either. I know it's not good for these trucks to sit but I have several vehicles and just don't drive my truck that much. I'm thinking that the turbo vanes are sticking but why does the CEL come on ONLY after I start the truck, never under power or load. And again, the truck runs completely normal.
Thanks in advance, sorry for the long post.

P.S. The engine is BONE stock.