If not fuel, not electric, then maybe air? Check the air intake hose (that big one between air filter and throttle body) to see if there's any leak(as in any dry rotten crack), especially if there's an airflow sensor right before the hose, it will cause misfiring because of the inaccurate airflow reading. Then check all the vacuum hose to see if there's any leak.
If it's sensor, it usually will throw a code(and the "check engine" icon will light up) and you can read it using a scanner.