How to tune ThermoQuad secondaries?

I'm trying to dial in the secondaries on my ThermoQuad but I'm afraid the jetting is just way too rich. When I open them up there's a bit of a stumble then the engine will rev to about 3500 RPM at which it starts to misfire and kind of "flutters". Would this be an over-rich condition or over-lean? I have the air door spring set to about 2 turns and the tang is bent a tiny bit to reduce the travel from stock but it didn't seem to do much.