Fuel restriction spn95 fc 2343

[W9L]

So, in the last couple of weeks I have been getting this code and associated derate. Sent a driver out in it and it did it 4 times in one trip. You can shut it off for a few minutes and it seems to get rid of the derate. After he got back, I replaced all the stratoflex fuel lines, the return splitter tank vents, restriction sender in top of primary filter head and filters. After doing this the engine ran SOOOO much smoother and power and mpg up. I had been suspicious it was sucking air... I ran it 3000mi before it did it again. Also sounds like it is sucking air again. Just a flutter in exhaust. I put an inline sightglass between primary and secondary filters and find no air after it starts and runs a couple of min at 1000rpm. Injectors were all replaced about 80k ago and fuel pump is quickly approaching 400k. Everything I find on Quickserve seems to lean towards a restriction in lines for at primary filter. The restriction gauge with new sender rarely gets above 2in hg. Is this the same sensor that ecm reads and uses to calculate differential pressure ? I find it interesting that it was doing it several times a week before I replaced all the stuff and then waits 3000k before it repeats.