Engine Cutting Out

Well I just installed my new Weber 32/36 DGEV. Everything went good with that. I got all the extra vaccum crap and wiring harness along with the ECU out. It cranks and runs like a dream. Idles great, choke works good, but going down the road the engine is dying when I go from second to third. I usually shift at 3000 RPMs. Sitting in the driveway running I can rev the motor all the way up past 3500 RPMs and its runs great but when Going down the road it will sputter like its starving for gas. It has a brand new fuel filter and it constantly is full so I dont think its the fuel pump. I checked to make sure the carb is opening all the way at full throttle and thats fine. I am lost. I cant even drive this thing. Anyone have any ideas.

Just my .02 you could possibly have a weak fuel pump. not sure but your floats may be stuck tap on the carb lightly with a hammer handle or screwdriver handle.