2006 boulevard c50. No power and backfire
 

I bought a bike off of a friend and it has been sitting for 5 years. The bike was running well for about 5 rides then started having trouble getting any power when throttling and the bike cuts out when in idle. Listed below are the steps I have taken and can’t get any power. I also starting getting some backfire or a popping sound

- put in a new battery (pre running it)
- put in new spark plugs (pre running it)
- pulled fuel injectors and cleaned them (pre running it)
- drained fuel and added high mileage treatment to new fuel (pre running it)
- oil change and added full synthetic 10w 40 (after running it a few times and started having issues)
- added new oil filter ( after running it a few times ones it lost power and started having issues)
- added new air filter (pre running it)

I did all this work on my own with some help from a friend that is more versed in motorcycles. Admittedly I am a novice when doing work on motorcycles but I am pretty handy in general.

I am at a loss on this. Any tips or what the problem is?