All didn't go well last friday night, i changed plugs to what i "thought" was 1 step colder (3924 to a 3923), shouldn't have listened to the dickhead at O'Reilly's, come to find out its 3 steps colder, the car ran like **** NA, couldn't figure it out, so i only made 1 pass & called it quits, I need to find a plug thats 1 step colder then a 3924 Autolite.