I have a 289 with an edelbrock performer series 500 cfm electric choke carb. When I give the engine gas and then let off, it does not return to all the way tothe normal idle RPM but instead stays much higher. Sometimes I can drive around at about 15-20 mph without even touching the gas. When I put it in nuetral or park the RPMs surge even higher.If I just kick the gas pedal real quick and let off, then the engine will return to its normal idling rpm. Any ideas what could be causing this?

 

Replace your throttle return spring with a double spring setup?

High idle sticking?

 

I would definitely recommend a double spring setup, for safety if nothing else. But yeah, also check the choke and high idle and make sure they're adjusted properly.

 

Check for worn throttle linkage as well... Might want to go with a heim joint set up, check James W's website for info on this.

I have also heard (somewhere on the forum) that worn or broken motor mounts can cause the throttle linkage to bind. You might want to check this as well.

Yea I know this sounds obscure, but it may be an issue!

 

I have the same issue on my Carter AFB 540cfm (the carb on which the Edelbrock is based). Usually, I can just WD40 the linkage lightly and it'll keep it from sticking until it evaporates off again. I've gotten used to jabbing the gas as I let off. It's not as bad as yours, but it's there.

Twice, though, the high idle has gotten stuck. One of the reasons electric chokes qualify as strange beasts in my book.

 

are you running the stock 1" spacer under the carb? I found my edelbrock butterflies were sticking in the venturies of the spacer, and it simply took alittle bit of filing to clean up the edgeson the spacer to correct the problem.

 

Good throttle return springs ftw. And a double spring is required at a strip that enforces the rules properly. But yeah, sticking choke or throttle return spring, or something binding somewhere.

 

Aside from the above suggestions, you could spray it all down with Carb Cleaner.

 

carb cleaner ? doesn't that remove grease ?

as to the sticky throttle. had the exact same problem. and it seems to be very common with 65 models.
when I kicked it quickly it went back all the way to idle again.

a) if you add springs you'll get rid of the issue, but at the same time it'll be harder to press the accellerator.
b) what I did was to change the position of the return spring in such a way it would pull at a much better angle and stretched it a bit and results iun the same as a)
c) the only _proper_ way of repairing this is to check on the throttle linkage near firewall. There's a rubber where they are joint and I'll bet my breakfast that that is missing or only half existent ....

check this thread.
https://mustangforums.com/m_2951430/tm.htm
some pictures of my setup (the change which currently works) and a picture from soarings. where marked the red circle, check on that. That's been the culprit with a lot of us here.

Kalli

 

Sounds silly but in my world the simplest things have bit my azz.
Check to see if the heater hose is causing the linkage on the pass side to rub and stick.
My 525 Carter did that to me due to bad location I had on my hoses.