i havent flown the props for almost 15 yrs now so please excuse if am wrong.
you have a few options
1.you could get an engineer to take a look at it.
2.you could try to lean it on ground.
3.depending on your comfort level,your experience etc . give it a try at a safe altitude from which you could glide to the runway incase the engine quits on you and doesnt start again.
the best solution is to ask somebody very qualified on the type to answer your question and to be with you when you do try the above in air.
the props that i have flown we did have to lean the mixture at high altitudes else we had too rich a mix.
ALL THE SAME FLYING IS SERIOUS BUSINESS so take care and happy landings