Strange 6.0 Problems

[yfs200p]

Ok so my 03 2500HD has been acting a little weird lately. Every once in a while when i start it up and head down the road it shifts from 1st right into 4th gear. If i get out of the throttle, it will go back to 1st, but then when i get back on it it shifts back to 4th. I have to correct it by stopping to shut er down and fire it back up. Ive also noticed every time it does this, i look over and my electronic 4x4 shows 4Lo, even though it def is still in 2wd. It also says service 4WD from time to time, but never during this. I have the records from the PO, and when the truck was about 2 years old it went in for the service 4wd light, the dealer said a ground was corroded. Anyone ever heard of anything like this? Its annoying I wish i had the floor shift 4x4 like my old W/T...