Carcinogen
1/2 ton status
I thought GM used the firing order to identify the cylinders..?
The #1 cylinder is the drivers side front most one,,followed by #3,#5,#7..
Passenger side front to rear, is #2,#4,#6,#8..
So,your 2 cylinders with low compression are #4 & #6 ..could be the head gasket is blown between the 2 cylinders and only "leaks" compression,(and no coolant) when it gets warmed up..?..
Its a Ford...
And that is clearly the problem


..or take into consideration my short attention span...
..