Been fighting with my Millermatic 185....

Some tips I got from a friend who was a certified welder:

-Don't ever stand on the wire feed line (if you have feed issues you could have a bad or collapsed liner, they can be replaced)
-keep the wire feed line as straight or as large of coil as you can
-buy a Tweeco gun if you don't have one
-run the next size up tip than the wire
-use a cleaner pre-feed wheel (like the ear plug mentioned above)
-make sure you have a really good ground
-Practice