Distributor cap, plug wires, & plugs. Anything 'upstream' from the distributor, should affect all 4 cylinders.

Check the terminals (in the distirbutor cap) for #1 & 2. Check the wires for resistance, & also look for arcing (in the dark). Maybe for who-knows-what reason, the plugs themselves are fuel-fouled, & nothing helps until you put NEW plugs in.