The flavor problem may just be the wood. Some sort of whatever is not good. I don't know what you can get locally, but look for fruit or nut trees, white or post oak, hickory, or sugar maple. There are others, but at least know what it is. Split it to coke can/beer bottle thickness. Make sure it is seasoned but not too old and decaying either. The wood I use is usually 6 months to a year old, not multi year old (unlike what I burn for heat which I like more seasoned and lower moisture content).
I would give yourself a clean start. Raise your fire grate so there is at least 2" under it, 4+ is better. Build a nice big raging wood fire and get the cook chamber up to about 500* F. If there is any spilled drippings they will give off white smoke and then eventually it should burn clean. If there are a lot of drippings it could take an hour or more at high temp before the smoke clears, very little and it should clear up quickly. If you can get it up to 500 and the fire isn't smoldering, you should have enough airflow to smoke. If not, we have some design debugging to do.
Once it has stabilized around 500 for a bit and the smoke is clean, spray the insides down with a garden hose a steam clean it well. Let the fire die back a bit but maintain a pile of coals that will ignite a new split quickly. See if you can stabilize the fire between 225 and 300 adding a split or two every 30-60 minutes. Splits should ignite fairly quickly and burn clean. Try to keep most of the fire toward the end away from the outlet to the cook chamber. Keep the vents open for now and try to maintain a lower temp with a smaller fire NOT with choked back airflow. You can learn to dial back the air for later cooks after you verify that everything else works, but air is never a primary temp control on a stick burner, control comes from managing the fire. Smoke should be very thin and flowing steadily out of the chimney in a fairly smooth continuous stream. If you can smell it, it should smell pleasant, not bitter or harsh or chemically etc. If all goes well to this point, then try throwing on a pork butt. Otherwise come back here and report.
Once on to the pork butt cook, If your RF plate is over 370 give or take fats will smoke. Give yourself 1-2" or more of an airgap between the drip pans and the RF plate to keep the pans from over heating and to let the RF plate work. Any clean non-combustible spacer should work (tuna cans, brick pieces, cooling rack, whatever. Keeping a bit of liquid in the pan should also prevent any fat smoke. If the RF plate is below 350 and it drains, you will not need drip pans, but stick to them for now to help debug. BTW, an RF thermometer gun would be the best tool to check RF plate temp in different locations. Cook a pork butt unwrapped for 6-12 hours at 225-300 (time depending on size temp etc.) until it is soft enough to pull easily. You can wrap when done for resting/holding, but the key is it should easily be able to cook that long unwrapped without any hint of bad smoke flavor. This is a cut that is hard to screw up so it is a good test meat.
What is the chimney diameter and what is the cross sectional area of the space below the RF plate? What are the dimensions of the fire box and the cook chamber?
