My take is that you truly have a low fuel pressure condition. All the codes point towards this. All but one fuel pressure check says this. The one check that shows an adequate pressure is with the return line pinched off. That is a classic symptom of a partially failed pump (i.e. good pressure but only at a very low flow rate).

You don't seem to be reporting a problem during normal acceleration. Therefore one option is to lose the lead foot, live with it (i.e. no symptoms in normal driving) and hope it doesn't get worse.

Alternatively, you can continue tracing the problem back to the tank (e.g. bad pump? or clogged pump screen?).

My suggestion is to first try yet another new fuel filter. You wouldn't be the first person to get such a bad batch of gas that it takes more than one filter to trap out the junk. Granted in today's EPA controlled world gas contamination in storage is a relatively rare event. However for the price of a filter and a little labor this just seems like a good next step. When you do be sure to inspect the removed filter for junk. I normally just stand mine in a cup and look for particles to drain back out. If you find nothing then you have wasted a little time and now have a good trail spare. If you find a bunch of junk you may have found your problem.

Just my hopefully helpful $.02.