Rare here, humidity was high as I was being eaten by bugs and discovering the brilliance of the axle/disco design for the seal. I still have that 72 Vega GT hatchback...here with minimal rust btw.

Anyway, supper info in your post there. I picked up an old one wire, I'm guessing titania, 02 sensor for something. Now I check my "trim" by wiping the tale-pipe with my finger. Still coming out with black. I was toying with the idea of using that and the meter, to meter the mix.

OP...I'd think checking the timing might make sense. Just because you can't adjust it doesent rule out something odd. Agreed on checking the color of the porcelain on the plugs. I gather it's the front o2 sensor that controls the mix, might be until 99-2000, the rear only monitors the cat.