slight stringing  

Simple things to check:

1. Increase retraction:   The most important slicer setting is retraction.  This determines how much plastic is pulled out of the nozzle.
2. Dry your filament:  Hydration will destroy print quality
3. Retraction speed: This determines how fast the filament is retracted from the nozzle. If you retract too slowly, the plastic will slowly ooze down through the nozzle and may start leaking before the extruder is done moving to its new destination. If you retract too quickly, the filament may separate from the hot plastic inside the nozzle, or the quick movement of the drive gear may even grind away pieces of your filament.  
4. Temperature is too high:  If the temperature is too high, the plastic inside the nozzle will become less viscous and will leak out of the nozzle much more easily. However, if the temperature is too low, the plastic will still be somewhat solid and will have difficulty extruding from the nozzle.
5. Long movements over open spaces:  The length of this movement can have a large impact on how much oozing takes place. Short moves may be quick enough that the plastic does not have time to ooze out of the nozzle. I have experienced this with Octolapse and moving the print head to thei corner for better photos after each level.
6. Movement Speed:  Too fast equals more stringing and less quality.  

I hope this helps.  

If this is a new problem using the same filament and settings...

If the stringing is a new problem with the same filament and settings you used previously, I wouldn't change any slicer or printer settings without 1st eliminating physical issues:

1. Be sure your filament is dry. Wet filament can cause stringing. This is particularly a problem in high-humidity areas.
2. Consider calibrating your extrusion multiplier for each filament. Any variations between your slicer settings and the actual filament characteristics can cause small amounts of over-extrusion that contribute to fine stringing.

I've got some notes on fighting fine stringing that you might find interesting. I don't make any hardware or slicer settings changes without first making sure it's not one of these problems.

example

Other notes

This is an example of what I am seeing.  Although I have not dried the filament, it is only about a week out of the bag and has been kept in a fairly dry space with air conditioning.  

Filament can absorb moisture quickly

If you're trying to add pics, either drag them to the text edit box, or use the Add media button above to upload them 1st.

It only takes days under the right atmospheric conditions. PLA is normally not overly prone to absorbing moisture. Here's a pic of results I was getting at the start of a project on Dec 31st:

Here's what started when we had some unusual weather before Jan 3rd:

Here are the results after drying the spool on Jan 14th:

This was Paramount PLA. If you're getting unusual weather, don't underestimate how quickly it can screw up your prints.

tried a new roll

I switched to an unopened spool and the problem might be slightly better but has persisted.  I increased the z pull and it helped some.  Any other ideas?

Extrusion multiplier, then... it depends

Posted by: @dan-4

I switched to an unopened spool and the problem might be slightly better but has persisted.  I increased the z pull and it helped some.  Any other ideas?

I'd try calibrating your extrusion multiplier next. I've got some detailed notes on how I reduced fine stringing here that might be helpful.