Rough Fluttery Idle/lack of power on start up

Hey guys, been a long time since posting on these forums but hoping as usual here to get some good input.

The truck on questions is my dads 2005 f250 super duty with 6.0L

The history on the engine is that it had an egr cooler failure a few years back with took out the IPR valve. Those were replaced by a third party shop with a new valve and upgraded cooler.
Not to long later the valve went out again and my dad took it to the dealer.
A new valve was installed as well as a new pump due to "metal in the valve screen"

This is a couple years later now, truck runs fine when warm but when first started up cold it has a Fluttery idle and if you take off it is very unresponsive to the pedal. You really have to lay on the throttle to get things moving and it sometimes acts as if it is starving for fuel to me

Where we live in never sees temps below the 30's and it doesn't matter if it is 60 or 30 the symptom is the same.
I believe he is using power service additive since when can't find stanadyne in the area we have moved to

No codes come up from the computer and no engine lights.

Any thoughts?

Thanks for any input