I have a 2003 gmc sierra ive had a sony video system installed with interface?

[Dan Gerrow]

now the truck has been stalling could it be the interface unit causing the problem

 

[Molson02536]

now the truck has been stalling could it be the interface unit causing the problem

Try cleaning your throttle body with throttle body cleaner first. The IAC (Idle Air Control) valve my be sticking from carbon build up.

Try that and keep us posted.