Intermittent crank no start?

Hello. I'm currently experiencing an intermittent crank no start issue with my vehicle listed above 1500. It has been driving me crazy for months and I'm at a loss for where to go from here. The issue first started about 2 months ago when I filled up my tank with gas, the van started rough (cranking longer than usual and sputtering a little). Then after I parked it for the night it wouldn't start at all the next morning. It would start right up with starter fluid then stop when the spray was stopped so I assumed it was a fuel delivery issue. However, I was getting fuel up to the Schrader valve and could hear my fuel pump running, so I wondered if it could be the antitheft system (I believe it should be pass lock with this model but can't confirm it) which cuts power to the fuel injectors. I tried a key relearn procedure that I saw on YouTube and after not starting all day my van fired right up. However, I believe this was probably a coincidence because that procedure has not worked during any of the crank no start episodes afterwards. Also, my engine turns over without a key just by twisting the lip of my ignition cylinder, so it seems unlikely that there is an active antitheft system. I next tested my fuel pressure with a test kit and found that it was reading a bit low- around 55 PSI koeo which is out of spec for the 60-65 PSI koeo I'm supposed to see. I learned that the poppet nozzle injectors I have in my csfi fuel injection system are super sensitive to low fuel pressure, so I decided to replace the fuel pump. I ruled out the pressure regulator because my system was holding pressure super well for a long period of time even when I switched the ignition off. I also started by replacing my fuel filter before replacing the pump and I saw a temporary increase in fuel pressure and the van drove fine for a couple days before the problem came back. I checked the new fuel filter, and it still looks good so that's not the issue. I also started to notice that whenever my van would break down and then get towed it would work immediately after being towed, so I thought maybe there was debris getting stuck in my fuel pump sock that was getting dislodged during towing. I replaced the fuel pump and was now seeing 62 psi koeo. However, the issue is still coming back about every 4 days. I will first noticed that my van cranks for longer than usual and starts a little rough (sometimes it skips this step). And then after I park it if I leave it for a little while, even just 5 minutes it will crank and then sputter and die and just crank and crank after that. I have realized that whenever this problem appears I can temporarily fix it by jumping up and down on my bumper for a couple minutes. It will then start up and drive fine for another 4 or so days before it starts to start rougher and rougher, or occasionally just crank no start out of nowhere. At this point the van is extremely unreliable and can't even really be used. I wanted to add that I can always hear my fuel pump running when this issue occurs. And I consistently check all of my fuses which are always fine. I also scan it for codes frequently and only ever get a p0157 which is low voltage to o2s b2s2. This makes sense because I don't have a catalytic converter. One time clearing the code when my van was broken down got it to start right up, but it hasn't worked since then so it must have been a coincidence. The issue also doesn't seem to be temperature related, it has occured while the engine is hot or cold and in different weather. I have not been able to find anything weird by reading live data on my code scanner. Any input would be very much appreciated. Thank you in advance!