Hard starting 5.7 liter Suburban

I have replaced the fuel pump in the gas tank, replaced the fuel filter, changed spark plugs AND wires, replaced starter and battery with 800 CCA ; Suburban has 125,000 miles on it. When it starts it runs strong BUT it is hard starting in the cold Nebraska mornings. Would SeaFoam be an option? I really do NOT want to take off the manifold and replace the fuel pressure regulator, it is below zero and I fear it will not seal well