Code P0018, rough idle and occasional misfire?

Ever since I've had this car it's had some issues. The issues progressively got worse but after changing the MAP sensor, it got a little better. The car still has a bit of a rough idle, but the misfires have calmed down a lot. The car also seems to have some power issues, as the lights flicker slightly when rolling up windows and when idling. The only code that has popped up is p0018 which has to do with the camshaft/crankshaft in bank 2. The issue with it is this code pops up but goes away the next time I start the car every time. I'm not resetting the code with my reader and I'm not unhooking the battery. It's never around long enough to bring a mechanic to check out. It just disappears on its own but always comes back even if just for a little bit. Can this cause the rough idle and maybe the now rare misfire as well? Also, would this be more of a sensor issue or the camshaft/crankshaft itself? I appreciate any help.