My 235 6cyl has developed an intermittent misfire only after the engine warms up. I've rebuilt the 1 barrel carb, replaced the coil, plugs, wires, (distributor cap and rotor are fairly new) vacuum advance, intake/exhaust manifold gaskets. 3 other options that I have come across could be a low...

on my home from work today my car was periodically faltering. i think its a misfire, but i did take off the pcv tube and put it back on during the night. i was checking for discharge or oil in the tube. there is a lot of sludge around the pcv valve on the cylinder head.