2003 F115 now takes several seconds to start

When I go to start engine either 1st time after sitting or out and about on and off, it now takes several seconds of cranking to start. It's been happening about the past year. It starts, no problem, and runs WOT and all throttle positions all day long as needed, it just doesn't start in the first 1-2 seconds like it used to. Buddies '08 F115 does the same thing since he bought it used 5 years ago, maybe 5 or more seconds, he just thought it was the way the engine started and I would say, No, its supposed to start like this, and crank mine right up soon as you turn the key. Now mine hesitates a few seconds. Due to general maintenance, (not really to address this issue) last month, changed Oil, lower gear oil, changed fuel filter in the engine, new spark plugs and I even had to replace the main battery cable to the engine. (corroded the ends after 17 years). I heard through others to check fuel rail pressure, I get 36psi on my gauge at the fuel rail and maintains 36 after starting. I have not yet replaced any fuel pumps or VST... Thoughts?

Do you start as soon as you wake up? Or do you want just a few minutes more in bed? That motor is 18 years old, and you expect it to start as soon as you touch the key. Good luck.