Cleanign the carb will do a lot. Mine was very dirty, because of rust in the tank(car was stored a major part of its live when I bought it). The car started as a pif and eventually would stop idling and running completely. I replaced teh complete ignition and it didn't help(remember, diognose first the fix it ;-)
Fuel becomes reddish and red stuff (very fine rust) stays behind in fiel lines and the carb and the jets. It is so thin it passes your fuel filter without problems. My carb went back into the ultrasone cleaner 3 times before it was up to the standard of the revision mechanic. He told me to replace the tank or I would be back in six month.
The same stuff also generates currency leakage on your spark plugs.
Probably another good check is your contacts in the ignition switch in the steering column.
Currently driving a type 1 33, 1.3
Past alfa's 1998 3.0 GTV, several 33's