Intermittent Problem Starting 2000 Grand Voyager

Hi. I’m having am intermittent problem with my 2000 Plymouth Grand Voyager, and so far have not been able to find a mechanic who can help. Occasionally (usually after having sat for two days or more without having been driven) the van won’t start. The starter and battery are not likely the problem, as the car turns over, but it just won’t “catch”, almost as if there is no fuel getting to the engine. After doing nothing with the van but letting it sit for several hours, it starts right up. Has anyone else had this problem? Any ideas or suggestions? The mechanics say they can’t diagnose or fix the problem, because it’s sporadic and (obviously) not happening when I bring the van in. I would greatly appreciate anyone’s help with this. Thanks very much!

Connect a fuel pressure gauge and check the fuel pump pressure while cranking. Should see 49 psi.

Thank you so much. I will do this.