Hi, also my first post. You could have the not uncommon fault of the hitachi carb that it's leaking air into the engine from somewhere. In many cases the float chamber top plate screws have been overtightened, which warps the top plate. This makes it impossible to get an airtight seal on the joint.

Remedies include filing or carefully hammering the mating surfaces flat or getting a good replacement carb.

The linkages are installed correctly if opening the throttle also operates the accelerator pump and if pulling the choke opens the throttle valve slightly (manual choke). Check the carburettor adjustment instructions from the club wiki.

Good luck!