Hello All, I'm new to this forum and I need some help. First "yes" I used the search function. I have a 1987 90hp Yamaha, coming in the other day the motor started making a faint knocking sound that is consistant with the RPM. When I run it up to WOT it surges like I'm closing the choke on and off. Any ideas what may be going on? I use ring free at every fill up so I don't think I have a carbon issue.Any and all help is appreciated, thanks in advance.JR