Oldschoolcuda said

You most likely have gunk in your idle circuit from sitting/crap fuel.
Remove needle and spring assemblies from top of carb. Remove idle screws from front of carb. Blow compressed air thru each opening of removed idle screw. Re-assemble and adjust idle screws (about 2 turns out each) is good staring point. Start up then re-adjust idle screws as needed. Turn one at a time until she starts to stumble then back out a half turn or so.

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Lustle said

If you have verified that the choke is good. That there are no problems with the high idle. And that the curb idle is set properly. Then next I would:

Rebuild the carb. Break it down entirely. Soak everything in carb cleaner/acetone overnight. Being sure to remove any plastic parts of course. Blow carb cleaner through it (pressurized can type). Then blow compressed air through all the passages. Re-assemble. And follow AJ's guide to Transfer Port Synchronization to properly set it up for idle.

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