2002 Tracker by Mercury 60hp issue.

[Jcbwaters31]

So I’ve got a Tracker boat and it’s got a 2002 Tracker by Mercury 60hp 2 stroke on it and I’ve noticed something that concerned me. First off the motor looks to have been used very little. The boat it’s on that was bought as a package in 2002 still looks amazing. Anyways, I noticed that when I do a cold start and give it some throttle and hit the choke it starts right up but if I have the throttle too far forward it revs really high and will pop like it’s running lean. If I back the throttle down a little it won’t do it. Never does it while idling. I had the cowl off and I thought I saw puffs of exhaust come from around the motor. Is this normal when rpm’s are too high and not in gear? Some posts have said that it may be a crank seal. Really hoping it’s not that. Just spent $400 on a preseason tune up and the shop never said anything about it doing that.