03 Dodge Ram 1500 wierd trans problem

Anyways I have noticed sometimes during the first time I start the truck of the mornings the trans doesnt down shift on its own.
I back out of the driveway, then select drive pull up too my driveway's stop sign and when I take off it starts in 2nd gear, and doesnt want to shift into high and OD on its own very good either. After I drive it a mile or two, kick in in neutral, turn the ignition off, and restart the truck it works perfectly normal though out the rest of the day, unless it completely cools off.
WTH?
I was thinking the computer controls this (shifting), but why doesnt it shift out and downshift like normal? What does turning the truck off, and restarting do it? I mean the computer doesnt loose power?

Try cleaning your battery terminals (don't laugh) Had a 91 Spirit that had shifting issues (wouldn't shift into OD IIRC, been a few years lol) and that would cure it. It also had a bad habit of going into limp mode if you idled it too long or stopped, backed up and then went to go again. Took off in 2nd and stayed there. Learned quickly that when you flash the key on and off to reset the ecm but not stall the engine that you need to be in neutral. Tried it once when buzzing at about 4500 in 2nd and it started over in 1st. Ziiinnnnggg!!!

Never did find out why it did it. Trans shops don't diagnose problems anymore, they just hand you a bill for $3500 and tell you they had to re-build it. I drove mine for years doing the neutral re-set thing as required.

Kevin