I have a 2002 that lags 3800 -4200 when cracked open. Runs fine off idle 2 3/4 on pilot. It's worst when motor is hot and not too bad when cold. Cleaned stock carb and tried 130 main .040,060 shims . Checked for air leaks and checked plug color was a little soft black. Sea level and 60 degrees. Didn't see a tear or hole in carb diaphragm . Compression 125 psi and clean air filter. Could this be a vacuum problem ? or ?