OK, you said the magic words! Time to do some carb work: Check fuel pump pressure, I like to see under 4, but just so it's not 9 or somthing. Fuel filter: paper element type, be sure it has not started passing dirt (assuming there is one on fuel pump still?) NEW if in doubt. Float needle and seat: get viton or some resilent needle seat combo, and setting float level needs wet needle and top rotated 90 deg so there is no force on needle (as is, upside down) NOW try readjusting, and during warm up not when motor is red hot, and see if idle isn't smooth (Grin) Complications: Smog equipment? Some had a thermostatic air valve on manifold, opens when it's hot, screws up idle mixture no end! (one carb had it inside) . All above was often the customer who came in with "I need new plugs" (and didn't)