Don't bother too much about the voltage readout jumping up/down a fraction of a decimal or so, as this will not translate 1:1 into noticeable temperature changes. Hot resistance of the heater is fluctuating a bit, till the unit is heat soaked and thermal equilibrium reached. And if the readout is a bit too sensitive, it'll just display these minute resistance changes as voltage drift.
Best practice is to heat soak the unit for about 20 minutes at 12V, once you've plugged it in, till the shell gets warm to the touch. Then turn down the voltage to your desired temperature. I usually go for .5 steps in voltage input, when testing out, which setting/temperature I like best.
What's the problem with the Nylon Stem/NonG exactly!? The small stainless steel tips are usually the harder hitters with Log Vapes (in comparison to the glass stems & adapters, that are designed for larger loads)
, though they are also designed as one hitters!
Rule of thumb with the Nylons: Don't push in their screen too deep (5mm to 10mm depth max should suffice here) and don't overpack them!
Best practice is to load them up, by sucking your flower into the steel tip like you'd do with a straw. Then give the load a slight tap with your fingertip to even out and flatten the surface (don't compress it), remove any overhanging bits and pieces... and then simply insert them into the Doggie's core and take one nice, deep toke! Should produce a fat cloud immediately.