So, i bought this truck used, obvi... it has 200k, the guy i bought it from was.... idk how else to say it lol, a gang banger... 🤣... anyway, when i bought it i could tell it needed ball joints, tie rods etc... he said the cel was "the fuel tank pressure sensor" and because of that the vacuum was ****ed up, and like an old car with a bad choke, keep it revved when its cold... once it warms up, it will stay running on its own... (whatever... i got it for less than the cost of the lift kit itself) i leave and take it straight to autozone, run the codes... p0300, and 2 evap codes... one is legit the tank pressure sensor... the other is the purge or canister vent... they dont effect driveability and cause misfires... anyway, i go to the junkyard looking for a dash bezel, and grab a newer style fuel spider and test it, its good... the truck runs great... i warm it up, drive around for about 20 mins, no misfires, no problems at all... oil pressure was up... (i forgot to mention that as typical with chevy, there was noticeable fluctuations in oil pressure... typically it should read around 40 and go up to around 60 when youre on it... but this was like 10-15 at idle and up to somewhere around 50 when accelerating).... i shut it off cuz it was about 9pm and starting to rain... the next day, i go out to start it up and drive it to the shop where im gonna do the front end... it cranks and cranks and cranks and cranks until the battery dies... when letting off the key, it does like this weird backfiring thing... (in researching that, it led me to an ignition switch thread from here... one of urs 🤣 )... where it like rumbles but doesnt actually fire... found out that was coming from a no spark condition... fuel pressure was 58-54... leak down test was ok... a bunch of chevy techs say thats not enough... checking the "max operating pressure" of some of the new pumps and they max at 58 so thats straight bull****... something dumbass book techs say... theyll tell you, do a cap and rotor, change the plugs and wires, its your fuel pump, its the ignition coil.... the actual shaft to the distributor wears out... the bushings get worn, the gear gets worn into razor thin teeth and grind off... but guess what... that shaft, CONTROLS EVERYTHING!!!! That shaft is driven by the cam, and on the bottom of the shaft, is a gear that turns the oil pump... if the bushungs wear out, the rotor doesnt spin the way its supposed to, causing it to miss timing, causing the oil pressure to be sparatic, causing "camshaft position sensor"and "crankshaft position sensor" codes, when in fact u may find the sensors to still be good... changing the distributor is simple... the distributor shaft only goes one way, the cap goes one way, theres a stationary bracket so you cant mess it up... you may have to turn the oil pump shaft with a screwdriver to get the distributor to sit flush and flat... its like idiot proof for real... IF IT DOESNT SIT FLAT AND FLUSH TO THE INTAKE, THE OIL PUMP IS NOT ALIGNED... THE ROTOR SHOULD POINT AT THE "6" AND THE BRACKET SHOULD SIT FLUSH TO THE INTAKE.... but, by only changing the cap and rotor, it isnt gonna solve ur issue... the p0300 is caused by a bad or worn distributor... You will still be able to spin the rotor, you will still be able to spin the oil pump drive... the gear will turn everything still, but if you hold the shaft and spin the rotor, you will see that the gears turn but there is slippage and thats what causes the misfire...

I really hope this helps someone because when it didnt start, and then it happened like that the next 2 times it rained, i figured it out... the moisture definitely had something to do with it.. i noticed several other threads about this no start cond, where "it rained" was a common factor... i became a member of this forum because a combination of threads from here and some you tube videos really helped me out nailing this down... also, if you are gonna do the fuel pump, cuz it absolutely is a thing on these, autozone sells one for 176, thats the one i was talking about with the 58psi... they sell an upgraded one for 180 that you have to ship to home, operating pressure 72.5psi... you will never have a fuel issue again... anyways, ill be posting more as im still working it out and im sure ill have a ton of more questions and input... sorry for the whole goddamn story but... hope it helps someone or some of you lol