My buddy has a Holley carb dble pumper 750 vacuum secondaries and electric choke. It had a gasket kit put into it last year. This year it has a bad stumble off idle until it gets on a plane. Once on a plane it runs great. The boat is a 21ft. Eliminator 460 ford. The boat ran awesome until we got it to powell and it would barely run at all( clouds of black smoke out of the exhaust). We pulled carb off and could find nothing wrong. As a guess i looked on the choke and turned the choke to the lean setting and it was fixed. When we got back to california i set the choke back to std setting. This whole choke vacuum secondaries carb has me ready to throw it into the lake (i'm not a mechanic or very good at tuning a carb). I run a mech. secondaries and no choke holley 750 on my boat and never have any issues.. Anyone have a fix or help? Or anyone have a Holley 750 dbl pumper, mech. secondarie & no choke for sale??