I noticed a slight "stumble"(for lack of a better word)when accelerating from a stop on slight inclines and by the end of the week it became worse doing it when accelerating from any incline and up into higher RPM. But I still had plenty of power. So I put in new Monark injectors, a valve job, new fuel filters and a Purge. Still have the stumble at lower RPM but has tons of power after the tun up. I have no problem hitting 80 at the end of the on ramp. Any idea's of where to look next? Could the fuel pump need something?