6 HP Mercury 4 stroke idle problem

[tmitchell5188]

I have a 4 stroke 6 HP Mercury long shaft motor. It has the gas tank built in. I've also plumbed it into my main tank with a valve switch. AT idle, about 800 RPMs, it runs fine. A slight twist of the throttle, the idle jumps way up, probably over 2000 RPMs. When trying to troll with my 17' aluminum StarCraft, I troll at about 1.8 MPH and it jumps to almost 3 MPH. It's kind of useless. I would like to be able to get to 2.0-2.3 MPH.

Any thoughts? The motor has probably less than 10 hours on it.