2005 F 350 Power loss Check engine light on

[melsa1]

Hello everyone,
I have this F350 Walk into my shop with check engine light on,loss of power delayed start up when cold long cranks, a month ago we replaced all glow plugs and fuel filter on this truck and was running fine:

Dtc P1464 AC demand out of self test ranje.
P0281-Cylinder 7 contribution balance
P0284-Cylinder 8 contribution balance

Above 2 probably bad injectors.

P0404-Exhaust gas recirculation control
P0405-Exhaust gas recirculation sensor A

I am thinking if the egr valve being defective causing the po281,284 i am curious if any one had these codes show up.

I just would appreciate it if some one can shed some light on this.

EGR VV:306
EGR cooler:488
INJECTORS:307.00 each.

Thanks Mel