Slight surging at cruise speeds - Help

[ohdear]

That would be the $450 one DJ ?

DJ you say "Full Service" dyno with A/F readings ? As this will tell you instantly if you have a fuel supply problem. I note also you say checked fuel pressure ............. just as important if not more so what about fuel pump volume ? You can have plenty of pressure but no volume. To get at drain tank and remove from underneath, pump and filter comes out as one. You can either buy the filter on it's own $450 + or the whole assembly $900 +
Cheers