Unfortunately, the extreme variation in CINETHP is known and is due to the many changes in the the universe over time. The universe statements for 2013 and 2015 are quite different, so even though you have accounted for the NIUs, it is not surprising that your figures vary. The drop is likely due to the month-in-sample universe requirement.
The ACS version of this variable (CINETHH) has remained the same over time, moreover, the universe has remained the same. However, it should also be noted that in the ACS this is a household level question (in 2013 and 2015 CINETHP in the CPS was a person level question).