I always preface my statements that are opinion, so here it goes, this is opinion, since I have not experienced algae. I will say that it is a fule contaminant, and that can not be good. Intermittant plugging etc could be part of your bad idle. If you have had maintenance done and they said you had algae and did not recommend anything, I would get a different mechainc
Here is what I would recommend, regardless of the cause of the idle problem, run a fuel conditioner for algae through the system, twice! When the second tank is just about gone, pull the fuel tank screen and change it, change both fuel filters, and then follow it up by using one more dose of Deisel Dr or equivalent and changing both fuel filters one more time. Filters are cheap, especially if you do this work yourself. Even if you pay a shop to do it, it is cheap compared to a clogged system. I would also recommend that when you change the filters that you actually look at the contents. You can do this for the engine bay filetes by shaking them into a glass kitchen mixing bowl and looking at the bottom! I always do this! Also, when you do the tank screen, use a large clean metal container, such as an old refridgerator drawer (enamled metal). You can easily see any dirt and or filter it through a paint filter. I do not recommend using any plastic, because it is hard to get clean and detect "new dirt".
The Partsshop sells the fuel additives!
Any experts care to share real life drama about algae?