A few days ago, all of a sudden, I noticed a very low (400-600 rpm), shaky idling issue coupled with terrible gas mileage... Today it started stalling at every stop unless I give it gas. I believe cylinders 2 and 4 are missing, though it's hard to tell because the idle is constantly fluctuating and randomly stalling. When I get into gear the engine runs fine (still crappy MPG) and when the choke is on it runs fine. I have new Bosch spark plugs and NGK wires replaced less than 200 miles ago. New fuel filter. Cleaned the crap out of the carb. I pulled the plugs and they look normal. Wires are certainly carrying a charge. No random arcs. No visible crack in distributer cap, terminals look fine. Pretty sure there is no vacuum leak but I'm about to do a carburetor cleaner spray check. Head gaskets look fine, no coolant leak or anything.
Could this be a problem with the ignition coil pack? I planned on picking up a better one anyways, hopefully tomorrow.
Could this be a thermostat issue? I flushed the radiator not long ago, I'm sure the current thermostat is 166,000 miles old.
PCV valve maybe?
What other checks/cleaning should I do before I go on a random part-buying rampage with money I don't have?? I certainly won't be driving this thing until I figure it out. Thanks