70 Suzuki 4 stroke jumping rpms at 3500

[DanielS]

Everything runs fine till i hit 3500 rpm then it starts jumping between about 3400 and 3600 rpm no warning lights are on i can slow her down to 3300 rpm and runs fine. When not under pressure she [FONT=helvetica neue, helvetica, arial, sans-serif]hesitates for a sec at 3500 but will rev right on up[/FONT], spark, compression, an fuel are all fine any other ideas what this might be??