Fuel pump? it would suffer at WOT, not so much at part. The pump just keeps the line pressureized, it would go WAY lean at WOT, if part throttle was effected.
I leaning towards a timing issue. It sure is a lot easier to type in a fix than to do it.
remove the predator tune and put back stock. do not just change the timing. not saying it isn't the fuel pump. bucking and surging deff. happens with MAF problems and timing to high. I have seen fuel pumps go out with fewer miles as well.
It was the FUEL PUMP. Apparently, it was dying a slow death. Tech put it on the dyno and checked the pressure over a few runs and saw that pressure was dropping big time at WOT.