So I have a 96 1500 5.2 I bought yesterday and when I got home I took some stuff on it and the truck got cold again. I wanted to move it so I went to put it in reverse and it stalled. I had to have no brake on or have brake and gas applied. Later that night I got it to full temp and tried the same thing. Stalled. So I tried drive. Same exact thing. Please help me

 

And also I just went to start it and had to give it throttle until it got up to temp to get it to run

 

You could have a few things here. First when was it's last tune up (plugs, wires, cap and rotor, and cleaning IAC)? I think it's either the IAC or two wire temp sensor

 

I called the previous owner and it had a tune up like 6 months ago but they never cleaned the iac

 

Try that first there is a good write up in the FAQ section. Read it, it's important because you can need up the sensor where you have to buy a new one.