Surging at idle, struggles under load.

What is your question?

I have a 1991 S10 Blazer 4.3 tbi, that has a surging issue. Whenever I come to a stop, it surges hard, and will die if I don't give it a little gas. The check engine light comes on intermittently, and pulls a code 42. The vehicle also seemed to struggle under load, it would sputter and stall when climbing a steep hill. It hasn't down this in a while tho, but I don't drive it long. Both issues seemed to happen when the engine was at a higher temp. I've replaced just about every sensor, O2, MAP, IAC, TEMP, ICM, Plugs/wires/cap/rotor, Coil, ESC module, Fuel pressure regulator, PCV. I replaced my old pitted coil pretty recently, and changed the ICM, temp sender, and ESC after. I also have a leaky valve cover. I have a video of it surging if more info is needed. I took it to a shop and they scammed me.

What makes this problem better or worse?

Long drives, under load, warmed up engine

How long has your 1991 Chevrolet S10 Blazer had this problem?

6 months+