You get the P1000 every time you clear the codes; that's the marker code for the OBD-II system to let it know that there may have been DTCs, and that it needs to get an "all clear" from everything it's monitoring. (At least that's how I understand it.) It sounds like that should automatically clear once the OBD-II system has gone through a complete cycle and gotten that all-clear.
What I'm saying is that whatever's causing the P1233 may be the root of the problem. It may not be throwing the DTC consistently, so it may not show up when you're looking for it, but it sounds like it's a recurring DTC for your car, so you need to chase that trail.
According to the blurb on FastPartsNetwork, the XCal2 can do data logging, but beyond that, I don't know...