2002 Cadillac STS hard to start

First, is your check engine light on? If so, have the computer scanned at a parts store like AutoZone. They'll do this for free.

Also, do you intend on working on your own car? If so, I'll need a little more information to help you.

Is your engine hard to start at any time. Or if you drive it for awhile, shut it off, will it start right back up? Or is it only hard to start after sitting for a long while? And once you get it started after a hard start, how does it run?

If you get back with me, I'll walk you through a fuel pressure check, since your issue sounds like a faulty fuel pressure regulator.