Don't count the little 390 holley out. A friend of mine had one on a 355 sbc in a long travel sand car. He had me rebuild the carb & set it up for off road use which only required spring loaded float needles & jet extensions. The engine was built to nascar spec & it's power range was 4000 to 9000 rpm. It was a nascar spec 390 holley though, not an off the shelf one. The engine made 605hp & 430ft.lbs.tq. As far as the edelbrock carb goes I'm putting money on the electric choke being out of adjustment. On the choke there's an arm that makes contact with a stair stepped bracket that's attached to the throttle shaft. After the truck is warmed up, disconnect the choke(make sure to insulate the power wire) than use a piece of wire to hold the aformentioned choke arm to keep it from being able to make contact with the stepped part of the throttle shaft. After doing this I'd be willing to bet your erratic idle issue goes away. If this solves the problem, put everything back together & loosen the 3 screws on the choke housing to adjust it(i.e. make the choke bi-metal spring tension tighter). As for the slight bog, that's a little more involved because the secondary auxilary air valve needs to be removed & the weights need to be ground a little at a time to tailor the secondary opening rate. Hope all this rambling makes sense & you can get the issues resolved
