My guess is that your shifting problems could have been caused by your chainline. Most mountain bike cranks use a 50 mm chainline and most road bikes use 45 mm. I use a mountain bike drivetrain on my LHT with STI shifters, but used a shorter bottom bracket to pull the cranks into a 45 mm chainline. I use the shorter BB because of also using A shimano 4503 front derailleur, which is built for a 45 mm chainline. It is the most versatile FD that I've seen. I have set up 5 touring bikes with this setup including 3 LHTs.
It would not hurt to check the chainline. If you are replacing the drivetrain this chainline will be important when you start mixing and matching components, e.g., STI road shifters/ brake levers will not work with the brakes that are currently on your bike without adding some Travel Agents.
Last edited by Doug64; 09-13-22 at 02:19 PM.