First everything seemed normal, but then i noticed that the nozzle pushing out the melted abs could not keep up with the movement of the extruder and the abs was sticking to the nozzle.
I've had my Prusa i3 8" for about 3 months and was recently having some extrusion problems. Mine was extruding too much material and it was bunching up and warping. I finally solved it by adjusting the E-Steps. It was kind of tedious but it solved my issues. You can find a guide here: http://reprap.org/wiki/Triffid_Hunte...ibration_Guide

I'm getting really, really good prints right now. I did switch from the Magma head to the JHead because the Magma kept clogging. I might try the Magma again soon now that I'm all calibrated. Good luck getting things settled down. It looks like you are approaching it the right way and being thorough. You'll nail it.