My car has had the spark plugs changed very recently, one of the older wires i believe has a worn spot on it, the distributor cap and the rotor have both been changed. It's running but isn't firing right. It used to run right at normal rpm and running speeds, but when i floored it it would sputter and not have any power, now it just happens all the time. Not sure what to do but I need it fixed ASAP i'm trying to sell it for a new car. PLEASE HELP