Today I just replaced my friends headgasket and now the car will idle fine but as soon as I give it gas it stutters and wants to cut off.

A little background on what made me thing the headgasket was the problem:
He told me that it was blowing white smoke, so this told me the antifreeze was mixing with the oil.
The throttle body was full of ****. When I removed the head the headgasket was damaged around cylinder two.
I checked my TDC adjustments with the cam gear and crank pulley, and they all checked out fine when I put the head back on the block.
So im thinking there is a vac leak somewhere because when I was inspecting the plugs, I noticed a hose connected to a sensor coming from the intake manifold to the charcoal canister
Can anyone tell me what the deal is?