I couldn't get a consistent bubble rate forever with that thing. Jayson suggested a blockage too, but I don't believe that was the case. In the end I just had to fiddle and fiddle and fiddle with the settings to get a consistent rate out of it. I was just about to give up on it after several months of that nonsense. In the end I discovered that my mistake was that every time I'd make an adjustment, I'd increase the pressure and then use a "more closed" setting on the needle valve to compensate (I thought a higher pressure would lead to more steady-state situation). When instead what worked was decreasing the pressure and using a "more open" setting on the needle valve. My theory is that the needle valves these things are using are not very good near the thresholds (i.e., if it's "mostly open" or if it's "mostly closed" then it's not at a setting where it has optimal performance, somewhere near square in the middle is where it gives consistent results). BTW Hi Dez good to see you, long time no see, hope things are well.
Anyhow I think I run my reg somewhere near 10psi now, which is about half of what Jayson recommended to me at the time. If I recall correctly Milwaulkee recommends 10psi on their instructions, by coincidence I was just reading them the other day.