Ok so I need some help. All started about 2 months ago when I was driving down the road it started to act up and have no power and ran rough so I pulled over and after turning the truck on and off a few times it fixed itself and ran fine up until about 2 weeks ago. Randomly when I would start it up it would act like it wanted to bog down and cut off and come back up to idle....if I cycled the truck on and off a few times it would be fine and I could go. Everytime it would be the same and no smoke. Then I finally got my dad over to listen to it hoping it would run rough when he was here because like i said it wont do it all the time and I may go a few days without it doing it and sometimes it will be everyday. Well when he was here I started it up and it acted different....it had a bad misfire and sounded like I was missing a cylinder and had white smoke coming out of the exhaust. Turning the truck on and off didnt fix it. So the next day I tore it all apart and took the valve covers off. All the injectors ohmed out fine and I started the truck up and it was running perfect. All injectors pumping oil like they should. Unplugged each injector one at a time and it changed the idle so my injectors I believe are good. I put everything back together and started the truck up and it was back to the bad cylinder again. I changed the valve cover gaskets/harnesses back in the spring. Its sounding like a wiring issue. Could I have got a bad set of harnesses? Or could there be another issue. This truck has me stumped. Any help would be great. Oh it's a 03 f250 7.3l with 252,000 miles.