Im not an expert on engines (yet :3), but i'd say some revving over time will help keeping the engine clean etc. When i had my mazda 626, i drove 10km with like pretty damn low rpms (started with 500rpm's @ 1st gear etc - not kidding, the engine was very good). Then the cilynders got stuffed or how do i say it ... meh, couple of revs and that cleaned 'em and i was able to drive flawlessy again.
It was a '84 Mazda 626 with 2.0L gasoline engine.