The "mechanics" that told you to put the stock air box back on the bike were either incompetent or lazy.
Maybe they thought you were so unskilled that putting the stock air box back on would be best for a beginner.
The mixture just needed to be richer for all the air coming in from non restrictive air pods.
Many younger mechanics do not know anything about carbs . All they know is how to plug in a laptop and tell the computer to fix the problem.
One more thing... So many people have already made these jetting changes a long time ago.
Many of them 33 years ago do not have motorcycles or are not on the internet.
But trust me there ARE people out there that could tell you exactly what jets and needle positions to use.
We just have to find them and ask around.
On a Roadstar Adventure.