I have a 07 gmc sierra truck with the 4.3 vortec engine. At idle the motor runs smooth when you give it gas it wants to spit or sputter . I put new fuel in a couple of months ago and truck ran fine . I have also put new plugs, wires, dist cap and rotor cap as well. Truck ran well for a bit then started surging while going down hill. Replaced plug wire for #1 cylinder then it ran good again. Went to go to work tonight and had a hard time getting it started, then went to give it gas motor felt as if were misfiring or jumping. Any ideas would would be great. Robert