Running on 5 at start.
 

so every now again but too often. once i start the jeep it runs really rough like its running on 5 and when u give it gas it sputters like theres a dead pistion in there. but after about 15 sec the 6th piston comes back to life. question is what would cause this problem .? the coils new the thing it sits on is new ( for got the name) and computer is fairly new spark p lugs are about 3 years old and wires. AND all injectors are less then a year old. could the plugs go bad after 3 years. theres not a lot of miles on them maybe about 15,000 or so i no they should last longer than that right?

pull them and clean them if your not going to replace them. 3 years is along time on spark plugs though