Mig splatter....

Very well could be the genesis of your problem...........
see this thread

http://www.jalopyjournal.com/forum/threads/harbor-freight-horror-story-mig-wire.164822/
The spool that I ran out was a HF spool, had 0 troubles with it. The spool that I am having problems with is from a welding shop.
Are you using 75% Argon 25% CO2? or Straight CO2? 75% / 25% tends to splatter less.

Using 75/25.