This sounds like a textbook feeding problem, Dave. If you're using the stock PEEK based extruders, they have heavy jamming problems. Your issue right now is 2 different things, first, youre using 230c on PLA, the nozzle is was too hot for that material, I never go over 210 on tall layers, but the jams will trick you to raise temp, which actually makes it worse. You're carbonizing the filmamet into a black crystals coating on the inner walls, the less the volume, the worse the problem will get. Second, the nozzle does not use a heatsink, and in this design, that causes the insulator to heat up and the filament squishes and expands outwards as it softens up, jamming it before it enters the pressure chamber. I tossed mine in the trash (literally, they're crap nozzles) and made an adapter for an E3D, have not had a single skip since I've done so. The grid has a heat problem in stock extruders, it's not designed for this kind of work. ABS handles It better but that's because the temp at which it softens is much higher and thus is effected less by this, but since there's no heated bed, ABS is more or less useless here, even though it's listed as being able to use it.
Cleaning these nozzles doesn't really work, and you can't open them up or change the tip, so u need to buy new ones when they go bad, which happens quickly, they wear down fast. But don't waste money on them. I will give you the file for E3D adapter if needed.
You can try to clean nozzle with finger operated drill bit but be careful as they snap off inside with any sort of horizontal torque, and then you're really in some trouble. Once you clean it, you can try to set 190 for 100 micron print, 195-198 for 150 micron or 200-210 for 200-300 micron. This will counteract the heat jam issue, but since you have toasted the filament inside the nozzle at 230c with PLA, the damage might already be done.
The down side of the E3D is that you lose build height but the quality improvements and ease of use and maintinence are night and day, it had my jaw dropping when I saw the difference. But I digress... I've made a new extruder assembily for it that acts as a riser to gain more height than you had to begin with, while allowing for much larger fans than the anemic bastardized blower fans it comes with for the build plate, and accomidates the E3D fans as well.
Try a clean and lower temp, let me know what you find. If you think this may be a stepper motor issue, testing is simple, just swap 2 of the motors and see if problem migrates. If not, it's your nozzle and settings causing it.
I can't stress this enough, the PEEK nozzles are crap. You are wasting your time with them and stunting your learning potential by using them. I've been running duel E3D V6's on mine for 2 years now and I'll never go back. It's not worth the trouble and cost of replacing a worn nozzle. E3D nozzles cost less than a dollar to change the tip, AND you can select different sizes for higher resolutions, whereas stock locks you to .4mm.
Hope this helps. If you need the adapter files, let me know.