2012sierrasle

I have a 2012 gmc sierra 1500 sle... took it to the mechanic for vibration issues at idle no matter what gear its in. He replaced the plugs and wires, maf sensor, fuel pump and hanger for the fuel tank. He also said the ac belt needed to be replaced and have the original gm gas cap put on which I'll do myself. The vibration is still there so my question is, will the ac belt cause vibration if its getting worn out since it's on the crankshaft?