I have a 1997 STS. Starts pretty well when stone cold and within 5 minutes or so after shutting down warm. If it sits longer than 5 - 10 minutes, (but not overnight) it cranks for 10 seconds or longer before starting.

Checked fuel pressure at the rail...40+psi. I'm currently running injector cleaner through it. So far no change. Any ideas or experiences appreciated.