Originally Posted by mwoodland

Though there is an overlap of symptoms that suggest some commonality, I think it might be different issues for different cars.
I just replaced the Pre-filter - with O-ring - and main filter, shortly after replacing all of the shutoff valve O-rings.
Based on the flattened profile of the pre-filter O-ring, and the fact that it cured the symptoms completely, I would suggest to do this first.
For those who have already replaced this with no improvement, I would suggest the next-in-line place for failure would be the filter housing-to-pump fuel line.
Verify that this has been retrofitted from the plastic clip version, to the banjo bolt version, as the plastic clip version was also a leak point.
In any case, fix all sources of entrained air, before beating on the high dollar solutions.. like new injectors, recessed valve seats, etc