Intermittent Hard Start

First start by checking the fuel pressure at the fuel rail. If it falls within specs, next try to borrow a set of noid lights, and hook them up in place of the fuel injectors. If I remember correctly this models injectors fire 3 at a time. Three should light, then the other three should light. Or they should all light on their own, but either way, all 6 should light. Have someone crank the engine while you watch the noid lights.
If they all light hook the fuel injectors back up. At this point you will have eliminated the fuel pump and electrical connections at the fuel injectors. It is possible that you have a failing fuel pump relay, as it primes the fuel system in preperation to start. They are fairly inexpensive, especially if you use an aftermarket part.
If everything here tests out just fine, please reply and we can do some more diagnostic testing.