Just replaced my transmission lines from the metal lines to te cooler lines. But now my transmission is slipping in and out of overdrive, and if you hop in the truck to go to te store you have to let the transmission idle for at least a minute or twofer the truck will even move. I'm wanting to know if anybody has had this problem and if they did what was the diagnosis? and what was the cost to fix it?

 

It might te torque converter locking and unlocking just thought about that

 

Try this in the mornings.
After it starts, move the shifter to neutral. If this helps it to engage gears a little quicker, it shows the converter drains back to the pan when sitting.
There are several causes. most common is the converter bushing is worn. It could also be the manual shift valve possition.
It doesn't hurt anything to just put it into neatral to refill the converter when cold. i'd just drive it. The other issue with unlocking the converter, start by cleaning the battery cables, especially the grounds.