I've got a Holley Street Avenger 570 cfm carburetor that is exactly one year old. The choke keeps getting stuck to where the motor stays revved up high until I hit the gas then the choke opens up then the motor revs down. One time the choke froze in one position and when I went to start my truck it sounded like a backfire or a timing chain popping. This has been ongoing and I would like to know if anyone out there has any solutions. I'm all ears.

Also I've been told there is a device with a gauge that measures your air/fuel mixture when adjusting the bleeder screws. What is it called and how much do they run? Thanks.

 

The fast idle cam will not release until you push the throttle a little bit. It is gravity actuated once the choke plate opens. It can not drop until you raise the screw up off of the cam by opening the throttle a little more.
An Air/fuel ratio meter can be used, but you will have to add an O2 sensor to the exhaust which will require welding a bung into the exhaust.
The easiest way to adjust the mixture screws is with a vacuum gauge. With it idling and warmed up, slowly turn them in until the engine starts to slow down. Then slowly back them out until you get the highest vacuum reading, then turn them back in about 1/4 turn.