2006 chevy 1500 z71, was neg 10, now won't go past 2nd..?

Negative 10 as in outside temperature? Vehicles don't like starting and driving when it is that cold. Check the transmission fluid, it might be a little low. When was the fluid and filter changed last? I like to change mine every 30K miles.

yes, it was neg 10 outside I let it warm for a few, but hit the road and at 40/45 it just climbs in rpm, oil pressure. Does not seem to be shifting past 2nd..

Colds plays hell with things and your truck is old. If you drive it long enough the transmission should warm up and (maybe) work correctly.

Also you can try replacing the transmission fluid temperature sensor. It's usually screwed into one of the cooling lines near the transmission. It may be sending the wrong signal to the computer about the actual temperature of the transmission fluid. At that temperature the fluid will be very thick and the computer will need to be able to adjust certain things in the transmission for it to shift correctly. Hope that helps! Jim