With the engine running and in drive but at a stop the vehicle seems like it is missing at times when the AC is on full blast. It drops as the AC is turned down and is barely noticable when the AC is turned off. Battery is less than a year old and I just changed the plugs. Maybe wires or cap and rotor? Or is it some kind of sensor or the AC unit itself?

In case anyone is interested it turned out to be the wires. I did change the plugs, cap and rotor first but it finally went away when I changed the wires.