Hi, mtjeep82!  So, you're making headway, the symptoms have narrowed to stumbling between shifts and the start-up problem/return to idle quirk.  Some thoughts...   Your fuel pressure is actually slightly on the high side (normal is 14-15 PS), but this is unlikely to cause the symptoms you describe.  You might readjust the pressure unless you suspect test gauge error...Given what you have done (plenty and good approaches!) and the remaining symptoms, I would adjust the Idle Speed Actuator Motor