Also check the petcock function while you're in there. They are often the cause of fuel starvation (bad diaphragm/vacuum leakdown).
I rebuilt the petcock last week. Thanks!
I agree with you, remove that extra filter, make sure the fuel line is as stock. Straight with no extra length.
The air box is only hard to replace because so many say it's hard and then you expect it to be hard. Watch DAG's video, makes it easy
Lastly, just because you rebuilt the fuel valve doesn't mean it's working properly. I went through that, very frustrating until I just got rid of it for a Pingel.