Ive got a 01 7.3 4x4 with 222k on it. Recently my mpg has dropped from a average of 14-15 to maybe 9-10. I noticed that crusing speed (50-55 mph) that my boost gauge is barely reading anything. I went through today and checked all the boots and retightened all the clamps on my pipes. Went for a drive and stayed around 2-3lbs @50. That seems pretty low to me still.
I can turn my programmer up and floor it and it will jump up to 26-27 lbs, but qucikly drop once i let off.

Any ideas what to do next?