Speed is really critical with a Mig welder along with gun angle. Are you grinding off the mill scale on the steel so you have nice clean material? What is the wire grade and thickness? How far is your stick out?
If your getting the "bacon sizzle" sound your settings are pretty good, just work on angle and working speed. Do some dry runs as well this will help with body positioning so your smooth with your pass. It was mentioned earlier about duty cycle, you might not be able to go over 10" when your cranked up.
Pure argon shielding gas? What setting?
