I've been working on some projects in my garage the last couple days and after replacing the motherboard in my 212 a few months ago my machine has been working very nice. Then this morning it was like someone flicked a switch and all my welds went to crap. The weld is building up like I don't have enough heat but I am using the same settings I have been using the last couple days. Almost all my material has been 1/8" with some 3/16". I clean all my areas with flapper disc on my angle grinder. I have been using the autoset feature as well. My bottle of Argon 75/25 was getting low this morning so I thought that was maybe the problem. I went and exchanged it at AirGas and the welds are the same or worse. Below is a couple pics.

I have a Miller 212. I'm using 0.030 wire with mild steel from my local steel place. This is the same steel I was using yesterday.

You will notice how I am getting black residue around the weld areas and when I turned up the gas pressure I get brown real close to the weld then black after that.

I am still using the same spool of wire and it looks clean.

This shot I am using 45 cfm gas pressure on the right and 25 cfm gas pressure on the left weld. I usually run lower cfm but when I had my machine in for the board problems the gent there said I needed to run more cfm. This is using the autoset feature on 1/8" steel.

This next picture is same heat setting with about 35 cfm gas.

I should mention that is does not sound the same when I am welding. It also does not look the same. The area around the puddle is doing some funky stuff as I well but I really have no idea how to explain it.