Howdy all. New member, joined because I'm stumped. '03 4L IL6 is giving me fits. Out if the blue jumped into limp mode. Threw P0306 code (#6 misfire). New plugs and coilpacks and got the same code again plus P0300 (random misfire) and P0315 (primary coil A malfunction). Disconnected battery while checking electrical and vacuum connections and ran fine after hooking the battery back up but now doesn't shift right. Starts out in second and shifts to third around 4k rpm. Now first gear or OD. Anyone else have these kind of issues and can point me in the right direction to fix them? Please help!! Been a great vehicle right up til when it wasn't!