Welcome to Iboats,
Seems the motor has 3 issues :
-The mixture screw is way off from ideal or the idle rpm screw needs a proper rpm adjustment.
-Being a 2009 year motor the impeller must be dried, hardened and already shot, need to install a new one. Has the motor experinced overheating issues on fresh or salt water usage ? which type of watercraft and length is the motor powering ?
-If the motor runs strong at wide open throtle with no issues could be :
Badly deck load distribution, improper trim setting, motor/transom way off from ideal, prop has too much pitch, without a wot test as usually loaded and without an induction tach install next to tiller will never know if the current prop it's doing its homework right revving midle to max wot rpm range factory stated...
Happy Boating
