There is one more important note here. While setting the fast idle speed, there is also a vacuum diaphragm called "the choke pull off" that needs to be tested. The diaphragm has a rod linkage the connects to the choke linkage. There is also a vacuum hose connected to the diaphragm that also connects to a vacuum port on the bottom throttle body. The vacuum hose needs to be soft, pliable, and without cracks or it needs to be replaced before the test can be done. You need to disconnect that vacuum hose at the carb base, and push the plunger on the diaphragm in all the way, then while its pushed in, cover the end of the hose with your finger to seal the hose. When you release the plunger, the plunger should stay sucked in until you release your finger from the hose end. If the plunger does not remain sucked in, either the hose or the choke pull off plunger is defective. Replace either (or both) of the defective parts. If the plunger remains sucked in until you remove your finger covering the vacuum hose, the choke pull off and the vacuum hose are good
The purpose of the choke pull off is to open the choke plate enough for the carb to get enough air when the motor is cold and the choke is in operation, so the motor can run. If the choke pull off and the hose are good, the next thing that needs to be checked is how much the choke pull off linkage is opening the choke plate. This test needs to be done with the plunger fully pushed in on the pull off diaphragm. You either need a vacuum pump to keep the plunger in, or you can push it in manually, and use something to temporarily plug the end of the hose. You will need both hands to check the gap between the choke housing and the choke plate. That gap is normally checked with a drill bit of a specific size (the instruction do lay out the process and the drill size).