Slow starting

Looking for help with my 1999 3.l L Pontiac Grand Prix. All was well until I had the Intake manifold seals replaced. They said the coils were rusty, so they were replaced along with spark plugs and wires. The car would then (at times) crank a little bit longer before starting. When I took it back, they said the fuel pump pressure was low, so it was replaced, but the problem persisted.
This has been going on for about 3.5 years now, so not a fatal problem, but getting worse this fall. I’ve had it in to 2 local garages that I trust and 2 local gm dealers, without any luck fixing it. Some say the fuel pump pressure is on the low end of normal, but I’ve been reluctant to have another put in.
Lately, seems like when the car sits for several hours it either cranks longer to start or will almost start, but need to be cranked again. Seems like I’m either not getting enough fuel or perhaps too much?
In the interim, I’ve had to replace a crank sensor and last week the transmission. Neither has had any impact on the starting issue, no surprise.
Thoughts? Questions?

What happens when you turn the key to the position right before start, turn it off and then right to that same position again? Do this maybe four times. Does it then start?