I'm telling you, it's the carbs. PJ's are a pain in the ass to tune. They have to be perfect. One main or pilot size off will make it run like shit.
Ditch the carbs. Get 35PWK.
I currently have my Laeger LT arms set up with Fox Float Evols that are 16.25" from eye to eye. I can't imagine throwing an 18" shock on there, but maybe you can..
I haven't even ridden on this set up yet. This is all brand new to me.