There's a lot of mediocre advice on this thread. I feel like people are just throwing out random stuff that has happened to their engine at one point in time in their life or another. So I'll play along and preface with that I'm a heavy DIY and engine problem solver. Based on the actual SYMPTOMS and HISTORY Going from running well in January to a bad idle now it sounds like you're describing that you need a thorough carb clean focusing specifically on the jets.
A flush isn't gonna do much for what you need at this point in time. If it were me, since I'm also cheap, I would not buy new ones. Just run copper wire through the old jets. Also used compressed air and do a very thorough job. Downside is if you do a bad job you may miss the obstruction in jets and still have the problem when putting back together (then I'd do it again). So if money isn't an object you could just buy carb rebuild kits for all-then you know for sure.
A flush isn't gonna do much for what you need at this point in time. If it were me, since I'm also cheap, I would not buy new ones. Just run copper wire through the old jets. Also used compressed air and do a very thorough job. Downside is if you do a bad job you may miss the obstruction in jets and still have the problem when putting back together (then I'd do it again). So if money isn't an object you could just buy carb rebuild kits for all-then you know for sure.