Mine does the same thing, it's annoying as hell at times but i'v grown use to it because i know what my issue is already. blown plenum...

 

What I described when it is on hills?

It runs good, don't get me wrong. And the downshifting thing is normal - the transmission is trying to adjust to get into the powerband -- the power just isn't there.

If I just keep it steady and don't nail it, it will hold speed and stay in that gear, but it throws a CEL for some misfires most times. I may try putting a new plug/wires/cap on it and see if it actually is misfiring, or if it just going nuts. Not sure what to think.

Superchips is ordered! Hopefully in the next week I'll get that and stabilizer done, and then I can get an alignment..Slowly but surely my dream truck