Spark plugs about a month old, but BLACK. Not oily, just sooty.

Runs rough when cold, smooths out considerably when up to temperature.

It's a 22R (carburated) engine, in a 1986 Toyota pickup.

Need any other info, just ask.

Sounds to me as though its running rich, plugs should be a sort of straw colour. Don't know if you have auto choke fitted, but if so check that is not stuck/nackered, if a water temp operated one check its not blocked with s**te. HTH Ray

I figured it was rich by the speed at which the plugs blackened up.

I can't see a level in the carburator sight glass - gunk in the needle valve, broken float, or just idle mixture out of whack?

Do I have to take the carburetter apart to change the float/fuel level, and how do I determine if I've leaned it off too much?

Is there a way to tell if the fuel mixture is right without a fancy computer gadget?