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I’m running into a problem with my 69 428 4 speed when it starts up it idles at 6.75-7 but once I start driving it within 5-10 mins (basically once it is warmed up) the idle sits above 10 sitting at a stop. If I punch the accelerator itll drop back down to 6.75 but once I start accelerating again and come to another stop, it’s back above 10. It’ll always go back down by just goosing the accelerator but then goes back up again after accelerating and coming to the next stop. Is the most likely culprit to investigate first the choke? What else would make sense as the source of this issue? I’m pretty much a newbie to car work so any any ideas Would be helpful.
 

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First thing, check to see if you have the throttle return spring in place from the bottom of the throttle arm, to the cable bracket. If not, you're relying on the spring on the throttle shaft. You could also have a sticking anti-stall dashpot, a binding throttle cable, or a damaged baseplate.

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After you verify that your carb hardware is working correctly, look for a vacuum leak. Metal expands from heat. Start with the intake manifold and carb base after the idle speed changes.
 

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6.75?
Do you mean 675
10?do you mean 1000

Check as mentioned and also the fast idle adjustment
Being that after you blip the throttle its then ok is telling me something is binding in the linkages
 

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My motor emerged idling high above 1800 rpm one day and creeped even higher when warmer. I found that tightening the four carburetor mount bolts reduced the idle down back to normal. I decided to replace the Edelbrock heat insulator carb nitrile rubber gasket (0.33") under my Holley carb. This happened when the car was first exposed to the initial higher temps in May in Arizona.
 
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