reason I ask is my sister bought the 150R up in glens falls when they first came out in 08 from a dealership…and the thing had power everywhere…this bog you talk about never existed with her’s.
you could re-jet it…usually a bog like that means its too rich…but its weird it runs good with the choke out. Could be a pilot yet or the carb needs to be adjusted from the outside.
you could put a smaller front sprocket on the front as well to help reduce bog.