1997 tahoe intermittently wont start

i have a 1997 Chevy Tahoe LS 4dr. 4wd. i have had a check engine light on for a long time. random misfire and cam/crank correlation error. i changed my plugs and wires and timed it and the check engine light is gone. however before i fixed this issue i was having trouble where it will start and run perfect but randomly not start. it will crank and crank but no start and then when it decides (minutes to hours later) it will start and run fine. no problems at all. i checked the fuel pressure and was getting avg. 50psi. i changed the pump and filter and still have this issue. what else could it be? i have 198,000 miles on it. when it sits in the garage overnight it seems to start fine but if it sits out in the sun all day it wont start. i dont know if it has any thing to do with it or just a coincidence. new alternator, water pump, plugs, wires, fuel pump, fuel filter, battery, all fluids are good.

a buddy suggested to change the fuel pump relay and add sea foam to tank so i did and i also tested the fuel pressure on my new pump. it primes to 60, a second or two later drops to about 50-52. started it and it runs at about 50-52. same as my old pump.... everything i can find says it should hold 60-65. is my new pump bad? or is there something else that can cause this?

put your gauge on it and start it back up, locate the fuel pressure regulator and while its running take the vaccum hose off the regulator and see if the pressure changes. it controls the fuel pressure in the fuel rail

a buddy suggested to change the fuel pump relay and add sea foam to tank so i did and i also tested the fuel pressure on my new pump. it primes to 60, a second or two later drops to about 50-52. started it and it runs at about 50-52. same as my old pump.... everything i can find says it should hold 60-65. is my new pump bad? or is there something else that can cause this?

fuel pump and the regulator maybe bad. airtex fuel pump? if so this is not a good choice. the fuel regulator maybe defective or the wrong one. you must be sure you have the correct regulator as some have used the wrong one and then lower pressures.

then the wiring of the pump ..any wiring that was cut spliced need be soldered. and sealed with heat shrink. ground connections at the fuel tank must be cleaned and secure.