If it wont pull into an in ground effect hover then you shouldn't fly it. You are either over gross weight or you may have an issue with the aircraft not making proper power or I've seen instrumentation errors where it says the manifold pressure is higher than what it really is so you are stopping short on the collective pull when there is more to pull. While the running takeoff is a good skill to have, outside of certainly scenarios you shouldnt need to use it to get the aircraft airbourne if everything else is good. How much do you and your instructor weigh? Does he show you the weight and balance for your flights? You should be covering WB by now in your ground school.