Engin hesitation, failure to start

I have a 1999 suburban k1500 w/5.7 liter engine 90k miles. Last dec I replaced fuel injectors, pcv, egr valves, distributer cap, wires and spark plugs, last week the fuel filter. 2 days ago the engine light brieflywent on as I was traveling at 60 mph and the truck started to hesitate. After pulling over and letting the truck sit for 30 minutes, the truck would not initially crank just turnover, When I had the fuel filter replaced I did a machine diagnostic test no codes popped up and the fuel pressure was 56 psi. Could this still be a fuel pump problem? Can weak valve springs cause a similiar type of problem and if so would the engine throw a code? Any help would be appreciated.