Yes Frank, it's a cheap little screw that keeps your powervalve from blowing. You heard it from my wife first

Signs a carb needs rebuilding, fouled plugs, rough idle, won't idle, bogs when you hit the gas, stumbles, idles way too high (common in 80's imports) etc. A lot of these things can be fixed with adjustments, but when you can't fix them by adjusting, it's time to rebuild. Carbs from the emissions era won't be adjustable. If you aren't sure, take it to someone that knows, if you start turning this screw and that screw, it will probably end up worse and then you won't be able to tell what the hell is wrong