I have replaced:
plugs
wires
coil
cap
rotor

I can drive in town and it is fine no misfire.
If I try to accelerate to get on the highway and make her work I get a flashing check engine light and it pulls codes for all cylinders misfiring and a random misfire code.
She doesn’t hesitate or choke or shake or anything that would normally suggest a misfire.

Any suggestions as to what it could be?

 

What plugs do you have in there? Standard coppers I should hope. These trucks REALLY don't like the rare-earth fellers.

Were you having the same problem before all the work? What plugs were in it previously?

 

i do have copper plugs in now. I started all of this work because it was having the misfire issue and the woman I got the truck from hadn’t replaced any of the parts listed since she bought the truck new.

 

The misfire detection uses variation in crank speed as seen by the crank position sensor. So the CPS could be the cause of "phantom" misfires.

 

Blown plenum gasket.
http://www.hughesengines.com/Index/p...p?partid=27091

 

I will check into this.

Is it possible for the gasket to still be blown and the truck to not use oil or smoke?

 

Yes.