chopperman

I am workin on a 2005 4-door 4x4, 5.4 ford dealer supposed to have changed cam phasers and cams,still runs bad, idles smooth,when u start giving it the throttle it acts like it is out of time,backfire and smother out,I made a fuel pressure gauge and put it where the fuel filter goes and at idle it has around 35 psi,when u give it throttle it goes to 38 then back to 35, need some ideas please,I dont work on many of the later model trucks so any info would be greatly appreciated Thanx Rusty