I use a Millermatic 140 with the automatic setting. The wire is .024 E-Z grind. Is 25-30 CFH or PSI, my gas setting is about 5 PSI as I do not have a flow meter, but even 25 CFH seems high. As far a welding , patience, patience, patience. Do not try to lay down a bead, just a whole bunch of tacks. I use five or six tacks and then move to the other end of the panel and do the same while the first one cools. I jump back and forth and keep checking the whole panel for temp and if it starts to feel too warm take a break and let it cool. Same goes for if you blow through, STOP and let it cool right down before trying to fill in the hole with more little tacks. This link might help, http://www.mig-welding.co.uk/thin-metal.htm