had this quad 2 years, problem just started this weekend. starts and idles fine, will allow full throttle in park. put it in gear and try to drive and it has no power, like it has a miss. pulled plug and it was coated black. replaced plug and put seafoam in tank. also sprayed seafoam directly into carb while running. still same problem. however, when i remove airbox it runs like normal. I'm leaning toward carb running rich,,,any thoughts?? thanks

 

Spraying Seafoam or any other carb cleaner directly into the the carb while it's running won't help clean jets,open orifices or stop problems that may be happening in the bowl. Pull the carb.