Randomly underextruding/overextruding small part on CR-10 I am printing fairly cheap, but highly rated, PLA and not sure whether this is underextrusion or overextrusion; but it just looks bumpy and not clean. My settings:

195 °C at 60 mm/s bed temp 50 °C
0.4 mm nozzle at 90 % extrusion
0.1 mm layer height
6 mm retraction at 60 mm/s with 0.50 mm coasting

I tried at 190 °C and it severely underextruded halfway through, but the outside looks much smoother; I also tried with and without coasting with no difference and tried adding -0.2 mm extra restart distance which didn't change much either. Could this be because I am just printing a rather small part (25 mm diameter)? I think this because I tried printing a much larger 100 mm diameter hemisphere just before, which printed perfectly using the exact same filament.
I've switched out to a new 0.4 mm nozzle, tried a 0.6 mm nozzle, but the only complete print I got had this rough and bumpy outside. It is printed in the orientation shown as removing support from those thin legs lead to them snapping.
I also had moderate stringing throughout, which I thought coasting and restart distance would fix.


Any ideas would be much appreciated.
Edit 12/04:
I have since reinstalled one of my all metal hotends, as I wasn't using them due to clogging issues, installed a brand new 0.4 mm nozzle, set the extrusion multiplier to 1.0 and disabled coasting. I also calibrated my e-steps, which means I needed to buy an arduino and burn new firmware.
Sadly I didn't print in between fixed, but these are the results I got.


The prints are much better but there is some pretty serious stringing and zits due to me needing to reduce the retraction distance for the hotend to 2 mm, as the 6 mm distance I was using before would make it clog; but since I'm using a bowden extruder it creates stringing. How could I go about fixing this? I feel like I'm playing a game of whack-a-mole.
The first one has major extrusion problems going on, possibly combined with issues caused by things you did to compensate for it or other issues. You should not see &quot;bubbly&quot; surfaces like that. There are a lot of things it could be, but my best guesses are wet filament, clogged nozzle or damage in the ptfe tube (if your printer uses one), and your 90% flow rate. If it was really printed &quot;right after&quot; the successful hemisphere that probably rules out wet filament and indicates a clog of some sort or your changes to settings.
Your retraction amount is probably good if you have a bowden printer but excessive and likely to clog with direct drive. Coasting and extra unretract are always wrong; they were a hack from a long time ago trying to simulate what linear advance feature in firmware does, but with a fixed hardcoded offset. Flow rate as low as 90% is also wrong unless your steps per mm were miscalculated. You can only go up/down by a few % without messing things up badly; there just isn't that much room for error.