Since I got my 73 Duster (with "reman" carb so said a receipt with it) its had a stumble issue right off idle with about a 1/4 movement. if held there the rpms would degress and start running rough and a bit more throttle would cause a stall. Only way to drive it was mash on the gas from a stop.

After tune, valve adjust, tear down carb keep messing and adjusting idle and af mixtures I thought I had it but started again. I read alot of post and one triggered my memory about putting a wire down the idle air bleed. so today i had it where a bit of throttle and it was running rough i put my finger over the air bleed and it smoothed out. So I took a piece of bailing wire put it down the air bleed and hooked it over the air horn so not to fall out. No more roughness at part throttle and 98 percent smoother.

So my question is Why? I do seem to have a small vacuum leak when I spray a bit of carb cleaner at the egr rod and have notice fuel coming out throttle shafts when not running as I was pumping the throttle so shaft may be a bit worn.

I hoping to not have to replace the carb so looking for advise on this.

Thanks Brian

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1973 Duster for sale

You just made the circuit rich so that will make up for or mask the increase in air (vacuum leak). If it is worn out throttle shaft bores, you will have to take it to a reputable carburator shop and have the bores bushed to tighten that up.