I have a 2000 Johnson 50hp outboard. It has become hard to start especially after running. I've been towed several times after stopping to swim. When you hit 3000rpm it surges to 4000rpm and does the same the other way 4000 to 3000. It's at the marina for the 3rd time and they can't seem to figure out what's wrong. Found a broken part on the linkage last time and thought they had it. Any thoughts would be appreciated.
