2003 ISX suggestions needed

[DDlighttruck]

Going out loaded 73K gross and running hard I got 5.2mpg (US gallons). Coming home, light foot loaded light, it came up to 6 mpg. I don't think that's horrible?

Finally got the right intake temp sensor from Cummins this morning, so that's installed. I guess next step is an overhead and PM Gearhead about tuning it.

Yesterday fiddling around fixing lights had a stick on the brake pedal. Found a brake diaphragm leaking. I knew I had an under the cab leak too, figured the vise grips fell off that cab air line bag. No LH turn or LH brakes. Shop threw on a new wire from the cab back, new brake diaphragm and turns out the secondary air tank is the leak. So luckily IH had one in stock got it changed after I finished loading. What a day.
Davco is mounted, new filter, and all clean inside. I'll wait until I'm back at the shop before plumbing the lines, they are there but I'm kinda superstitious about taking a truck apart while in the middle of a run. Leave it alone and finish the run.