'83 Monte Carlo - Miss fire at idle/accel./driving

An intermittent miss at idle that gets worse under load on a carbureted vehicled is almost always an ignition problem. The solution is simple and cheap. Put a new set of spark plugs and ignition wires on it, a distributor cap and rotor could be done as well if has been awhile since they've been done. This is just maintenance. If all of this has been done recently, replace the spark plugs again. They get dropped and cracked all the time in shipping or installation. This will likely solve your problem

You can have car put on scope and it wll show any irregularities in the ignition system. It can also be dowithout any equipment. First, loosing ALL 8 spark plug wires, Now place the spark plug wires loosly back on, just secure enough to secure. You might need 2 people. Being the miss is more consistant in gear, APPLY THE EMERGENCY BRAKE , put trans into drive and raise rpm's till miss is obvious. Remove ONE plug wire at a time, TILL THERE IS NO DIFFERENCE IN MISS. Thats the cylinder missing. Start with the spark plug, inspect, work back to wires and cap. An EXTREME result will be NO COMPRESSION.