Went ahead and fetched an EEC IV reader at the local parts store. Among other things, it had faults for running lean, which I confirmed is an active fault.
From there, I verified the lean condition by forcing a small vacuum leak, which killed the engine. I then restarted and used the carb cleaner trick… and found that I have a large leak at the carb base gasket.
I suspect my issue may be that I stacked two gaskets to try to reduce heat soak (something I read online would help with such). What happened was my carb kit came with a thin gasket, but not knowing such was included, I ordered such separately. The old gasket and the new separate gasket were a lot thicker, which I read provided additional insulation between the intake and carb. I also read of people stacking gaskets to improve such… maybe not such a good idea in retrospect.
Once the motor cools down a bit, I’ll pull the carb off and see what’s going on.