1989 Isuzu Rodeo Carbureted 2 3l Engine Pump Accelerator Quickly Will

carbureted 2.3l engine problem, if i pump the accelerator quickly it will rev fine with no miss but as soon as you try to push the accelerator slowly it will miss through the whole rev range, have played with timing, fuel mixture and used carb cleaner, thinking it must be a carb problem causing it to run rich, the chock linkage is broken but the butterfly is held open