@printHorst Here are a few random thoughts. Firstly pressure advance is designed to compensate for pressure in the hot end. Or more precisely, it will advance the extruder at the start of a move to compensate for the "lag" between the carriage accelerating and rate of acceleration for the molten filament existing the nozzle. Then at the end of a move, pressure advance will retard the extruder to compensate for the fact that pressure will build up in the hot end during a move, and this pressure will cause the filament to get extruded faster than rate at which the extruder decelerates. From what you describe, it seems that what you are seeing is "ooze" without any pressure in the hot end - just gravity acting on molten filament. Pressure advance isn't a universal cure for "ooze" in that situation. This is where retraction comes into play.
As you have observed, if you just extrude a few mm of filament but don't use any retraction, it will continue to ooze for a minute or more. This is just the effect of gravity. This is why we use retraction. From your description, I would say that you just need to get the retraction setting optimised. Both distance and speed can have an effect but every hot end / extruder and filament combination can act differently, so there are no hard and fast rules - you just have to find what works best for you.
Other things that can help. For sure thermoplastics in general become less viscous (more runny) as temperature increases. PLA has a particular problem in that it will hydrolyse over time. So it will become more and more runny, even at the same temperature. After an hour or so at print temperature, it will be almost as runny as water. So lower temperatures can help (I regularly print PLA at 185) but that depends on a number of other factors such as the melt chamber volume and the material that the nozzle is made from (generally you need use a higher temperature with hard nozzles which might be poor thermal conductors). Also, printing faster can often help. Faster still non-print moves can help stringing. Some filaments are more prone to "oozing" than others - even different brands of the same filament. Retracting filament as the final move of any print can help with oozing when you start the next print. Larger nozzles suffer more with oozing that smaller nozzles.
Essentially, if it's just "ooze" (which is what it appears to be from your description) then pressure advance is unlikely to cure it. It's just a matter of tuning all the other parameters (speeds, temperature, retraction amount, retraction distance, etc).