why is my welding inconsistent?

Wire feed rate dictates how much heat you're putting into the metal. Make sure the tension on your drive rollers is set right so the rollers feed consistently and don't slip unnecesarrily. Warn out rollers can cause slipping as well. Rollers should be a V-groove, not a U-groove.

I bought a used welder that came with pure argon gas. I couldn't do anything with that stuff. Traded it for a tank of C25 and what a difference.

I also switched to .023 wire which is better for sheet metal.