Is this a air circuit or a fuel circuit and does it require a special tool. Im having a very slight hesitation right off idle. Am I starting at the right adjustment for this problem. 87 firebird LG4 CCC all stock except cat back flowmaster exhaust but I can see the plug on the circuit has been pulled out. Fresh tune on everything else. Kinda looks hard to get to. Thanks. Respect.

 

Idle mixture is just that. The ammount of fuel during idle. It does nothing once the throttle plates open. Sounds more like the accelerator pump is starting to fail to me.

 

It's an air and fuel circuit.

But, you probably aren't starting in the right place. What type of air cleaner do you have?

 

New fram filter in a stock air cleaner . I was thinking the idle circuit would effect off idle low rpm. Now Im wondering if its the pump going bad. It only happens when I barely touch the gas. If I push it more than 1/8 it there is no hesitation or stumble.

 

If by "pump" you mean the accelerator pump, maybe.

Does the thermovac work in your stock air cleaner? Not having it will cause exactly the symptoms you're describing.

 

Yes I was talking about accelerator pump. I will check the thermovac. I didn't check it on recent tune up. I will post results. Thanks.