00Cherokee

2006 A6 Avant. No check engine light yet and starts up totally fine. It runs perfectly under acceleration, but driving at steady speeds it feelse like I'm pumping the gas. I've had the fuel pressure regulator go out on a similar year/mileage Volvo and it was doing the exact same thing, however eventually had the check engine light come on. Since it starts fine, idles fine, and accelerates fine I'm leaning away from the cam follower and fuel pump, but I may be wrong. Anyone else have this happen?