dt55 dropped rpm 1993

[ryanyura]

I have 1993 dt55/pu55 . Its a jet. It always runs at 5300 rpm and other day it dropped to 5000. Still gets on plane fine just max rpm changed. What would cause this? One person said to check the throttle position sensor on 2 carb as this talks to cdi. i checked the jet for blockage clearance and gate adjustment all is well down there. Is the throttle sensor what controls the max rpm of this motor? Operating range is 5000-5600 in manual. Any help would be appreciated. compression is all around 120 and I changed plugs and no difference and runs fine in the driveway so hard to trouble shoot at home. RYAN