it's the needles for sure.  if there is some plastic limiters on it use a pair of needle nose pliers and pull them off and use a small flat tip screw driver.  turn the low speed needle and wait till it idles good, then switch to the high speed and feather the throttle till it doesn't bog too much.  throw the caps back on if you wish and have at it.

I worked on Small Engines at a shop for 3 years and went to school for them for 2.  Common problem.