The trouble with moisture is twofold. First of all, normal home users can not measure how much is in a filament. Measuring the ambient humidity has no meaning in this context unfortunately. Secondly, even small amounts below 2 promille can cause changes in rheology, i.e. 2g per kg.
But of course you also need to ensure a clean nozzle. Flushing PAHT with PLA is not likely to be entirely successful. Try a few cold pulls with the hex key method.