Idle reading 450rpm in tach and stalling at start up. Once warmed up she will idle at about 650 no stall problems after that. Can I adjust minimal idle up to 650rpm to fix problem?

Why don't you fix the reason that's making it idle so low instead of covering it up?

And no, technically, you can't adjust the idle. If you look around the radiator core support, I bet you'll see a sticker that says something about the idle not being adjustable.

It's not wise to mess with the system this vehicle is electronically monitored and will utilize the cruise control cable to adjust need idle, if you go messing with it you will kick a code for high idle, you could have another issue with IAC (idler air control valve) remove clean with carb cleaner re-install with new gasket or high temp RTV