I just bought a 1995 SL750 over the winter and started if for the first time this week. I started right up, however the idle is so fast that it immediately took off (at about 1/2 throttle). The throttle doesn't seem to be stuck and when depressed, the jetski responds by speeding up. The jet ski will not sit still at idle in the water. At idle, is moves about 20mph. It takes off immediately in both forward and reverse. Is there an adjustment that I need to tweek?