02 Seville STS Starting Issue

Hello,
I just bought this 2002 Cadillac STS, it has 70K. Sometimes when starting it acts like it's having an issue turns over several times, but does start slowly, instead of a quick solid start. Car runs strong after start. Could this be a fuel issue, just bought new fuel filter not knowing cars history, haven't installed yet? Tried a bottle of Lucas fuel treatment in first tank, Ran OBT tool with no codes? Thanks ellis479

What is the standing fuel pressure? That may offer a solid clue.

I don't know, what should the pressure read on this 02 Cadillac 4.6ltr? Could it be a sensor that's just not showing a code on the OBD tool? I am not a mechanic, but have some common sense abilities. Thanks ellis479

It turns out to be the fuel pressure regulator was faulty. Thanks ellis479