2000 nissan frontier 110M/3.3L/auto.

full tune up done according to FSM.
cold starts on a split second. hot starts take 3-4 seconds.
If cranked for less than 3-4 seconds on hot start will not start. recranked immediately, starts instantaneously. also, if ignition held open for 4-5 seconds before cranking on a hot start, will start right away.
no other issues.
I'm suspecting a leaking fuel pressure regulator, a friend says leaking injector.
anybody experience something like this?

thanks.