I think you are running too hot in the vertical pos. I'm guessing you're putting an uphill cap on, am I right? Another thing you might try is more of a weave than an ocsillation. If you broaden your weave width and pause longer on the sides, fast across the middle, you can keep your puddle halfway round behind you. A lot of guys frown on this, but I can't run that big of rod uphill any other way. That's a lot of heat to run uphill. What thickness pipe wall are you welding, and what position,(6g),? I've never needed more than 5/32, personally. Good luck, I'm sure you will figure it out.