I am having trouble finding a good idle. I have noticed air bubbles in the line from tank to the carburator. I have an inline fuel filter between and the air bubbles start from the very beginning of the fuel line attachment to the tank. is this area supposed to have air bubbles in the line? I checked my o ring and the spring for seal strength and both seem fine to me.

There should not be any air bubbles in the fuel line. Your tank might be leaking.... Air bubbles will cause your engine to run inconsistent and throw off the tune of the engine...

I actually had this happen with my Ninja B01A and it was actually caused by the engine.... My rear bearing went out and had damaged the engine and I had a lot of air bubbles in the line.

It's definitely sucking air from someplace. I don't have much experience with Nitro cars, but I have 25+ years with R/C airplanes. You could have a pinhole in a line inside the tank. Look very closely at all of the connections and components. If all else fails, replace the whole fuel system. That may sound extreme but it beats replacing a motor that has leaned out from sucking air.

Pull your tank out and check around the seem for cracks also check the fuel line from the tank to the motor it sometime gets pinholes in it and if you have a inline fuel filter check and make sure it is not leaking.

also make sure the outlet from the tank is threaded in completely and tight