If you suspect air in the lines as a possibility.... Consider trying this.
First, this smoky blue,,, will the vehicle smoke while idling... ?? or perhaps, If you press pedal down in neutral will it get smoky?
Basically, run your fuel source from a pail... get some fuel line fill a bucket with some fuel and connect
your fuel source(a bucket) directly to the fuel filter... I would even consider running the return line into the bucket as well.
You are trying to either establish or rule most of the fuel system's lines/aparrati as the culprit......
Now, I have seen on my IDI a bad air problem... though, my symptoms being different....
my case was "fuel starvation" due to bad check valves in the feed and return lines...
(the most annoying symptom of this was rough idle)
Good luck , Monst