Intermittent no start- 02 7.3

[Vaquero45]

Not exactly a 911 but can be. On 3 different occasions ol' faithful was unfaithful. If 3 times is a pattern, this is what happens. Drive 30 minutes or so, shut it off and wait about 1 1/2 to 2 hours, cranks really well but no fire. Haven't been able to remember to check whether or not the tach moves. First time I hit the drain behind the fuel filter a couple times, fiddled with tubing behind filter then she fired up. About the same thing second time. Third time(last night), fiddled with tubes, cranked several times, let off some fuel, no luck. The truck set overnight (wife drove friends car home) and my buddy went out this morning, it fired right off....About ten different times throughout the day. When wife got there around 6pm tonight it fired right up, no drivability issues and drove the 30 minutes or so home. An hour later she went out and it fired up again like it should. She let it run about thirty minutes (7 to 7:30) and then when I got home (8:00), I went out and it fired right up for me . I checked the level in the HPOP and it was 1/2 to 3/4 inch below top. That was after running. Fuel pump ran for about 30 seconds with key on, before I cranked it. The fuel pump shut off on it's own, I presume it reached the desired pressure.
Worth noting- it has a Viper remote start and alarm, and a DP 6 pos. chip. Viper has been on about 2 years and DP has been on for 3 to 4 years, no notable problems prior.
Any suggestions, educated guesses or even shots in the dark would be appreciated!!
BTW- chip is 60, 80, 100 and 120. We usually have it on 60 when the truck is started.