I installed a turbo about 2 weeks ago on my 03 4.8L truck and got the tune pretty close. Suddenly (past 2 days) the truck goes very lean about 30 seconds to a minute after startup (every startup after it has sat for a bit) at first I thought my wideband was just off because it takes a bit to warm up and be accurate but I noticed as it read lean i could feel the truck bog down idling out of my driveway. After a couple good rev's everything goes back to normal. WTF? Havent touched the tune for over a week why now?