hey. i can't get my holley one barrel to idle. it runs fine when it's not idling. what can it be?

A vacuum leak:
Look for one between intake manifold to block, base of carburetor, power brake circuit if equipped, PVC hose, and any other vacuum driven devices that would allow additional air in to lean out mixture such as bad vacuum pods.

Crud in idle circuit in carb, and or incorrect float level.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

See here.

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