Motorcycle Repair: 03 Suzuki gsxr 600 idle / performance, suzuki gsxr 600, fuel tank

Question
I recently purchased an 03 600gsxr (6000 miles) fuel injected however the bike was down for about 3 mths before my purchase. My initial ride 50Km was ok but idling erratic. I then tried to clean the dirty original air filter last week without using an air compressor and since then more erratic idling and poor performance between 2000 to 4000 rpm along with a change in the health sound.
Is my problem air filter or dirty injectors?

Answer
That sounds like dirty injectors, drain your fuel tank, use a tank sealant (looks like elmers glue). That will keep your tank from rusting and allow you to clean out your fuel tank easier in the future. Use a fuel injector cleaning solution with your next couple of fill ups.