Ok guys, hopefully somebody can help with this crazy problem that I have been having. Recently changed out the cam phasers on my buddy's 2004 f150 5.4 with new dorman ones we purchased online from freedom racing. We also changed the spark plugs, oil filter, air filter, and engine oil with all motorcraft parts. The swap went fine and the install all went smoothly. However, after hooking it all back up and starting the truck it ran great and sounded real quiet. once driving it we noticed that it shuddered alot during acceleration and sounded as though a cylinder wasn't firing. It has thrown a p0354 code of primary/secondary D circiut malfunction meaning cylinder 4 or back cylinder on the passanger side. We swapped the cop with the one in cylinder five and had the same problem. tested the plug and found 14v before changing the spark plug to cylinder 5 as well. now when I pull the connector on the injectors in both cylinder 4 & 5 there is no change in the motor whatsoever. it still sounds like there is a cylinder or two not firing. I'm wondering if maybe the spark plug was jacked up from the manufacturer and is causing the cops or the computer to stop firing in that piston since cylinder 5 was working fine before we switched the plugs. Any help on the issue?