Force 85hp not accelerating

[Aramp]

Okay so the motor has been running great. Runs 35mph all day long with a skier behind and tubes no problem. It was idling really really high so I adjusted the idle down so it didn't burn so much gas. Well the next time I had it out, for some reason it would not get over 15mph. So I adjusted everything back to the way it was before I messed with the idle speed and still had the same problem. I had a feeling it could have been bad gas? I usually bought gas at a high traffic station, but this time I bought it at a small gas station by the lake. Could this be the problem?

 

[Jiggz]

I doubt it is the gas. Are you sure it is only the idle screw (at the bottom of the timing/control tower) adjustment you messed with? How about the idle mixture screw (in each carb)? How about the timing screw on top of the timing/control tower? You need to specify which adjustments you messed with before complicating matters for the worse.