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Hello all,

I'm very new to building and maintaining cars, with very limited knowledge of mechanics. I have a 1964 Impala with a new 350 Small Block, and a TH350 Tranny. More lately the past month or so, I have been having a high idle issue, which normal fixes itself with just a tap on the gas disengaging the choke. Now, after the car reaching operating temperature and after driving for about 10 miles or so on the freeway, the car will hit high idle in park. If I put it in gear, the rpm will drop drastically and it almost seems like it might stall unless I put it back in park. When I do put it back in park, it'll return to a high RPM again. If I let the car sit for a hour or so and go back to start, it doesn't start up easy like its suppose too, unless I step on the gas pedal. I should also note that I do smell fuel slightly, and the engine does have blowby coming out the PCV valve, and oil valve where the Chevy cap is located. I do also suspect a valve leak could be the potential problem, or maybe a bad fuel pump/filter. I have changed the oil filter about 2 months ago, and I'm not sure what the compression is yet. any thoughts, suggestions, or comments? I'm super new to this, and I would like to do it all myself instead of asking a mechanic to work on my own car. And I'm willing to post pictures or videos of the set up on the carb and whatever. Thanks for your time guys. :eek:k3:
 

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Welcome to the forum.

I see from your location that you are in California and I suspect that your very nice looking car may have some of that states "convoluted" emission controls on it ??

Once your car is warmed up and at "operating temp" as you describe and this high idle returns, while it's still running, remove the air cleaner top and see if the choke has not started to close again.

What carburetor is on this car ?

Is it equipped with an EGR valve ? ( i know in 64 there weren't such things, but, it's a new 350 and, California is in this mix so who knows ).

Maybe a picture of the engine room would be good to see what it is you have under there. ( air cleaner on and off, both sides around the carburetor as well)

Could be a vacuum leak that is caused by a thermal vacuum switch operating something open that is leaking.

Sorry to be so vague but there are a number of things that can cause this issue so some photos would be good to see, and also for you to have a look under the air cleaner cover after your highway run when the high idle reappears.

Let us know
 
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