Hi Christopher, my name is ***** ***** you for asking your question, I will try and help you out.
When you have low boost the two most common things are leaks on boost side of turbo which you already checked and low fuel pressure.
You need to maintain at least 30 psi fuel pressure under a load or you will have low boost and low power.
Verify fuel pressure by installing a fuel pressure gage in secondary fuel filter head,test drive with a load,if fuel pressure is low first change fuel filters if you have not already,next bypass suction side of fuel system with a temparray new line running directly into fuel tank about half way down,,tie up with some rags around tank opening and retest,,if you know have good fuel pressure and power you have a leak on suction side of fuel system such as a hose or filter head,if you are still low on fuel pressure replace fuel transfer pump and hand primer pump if you have one.
If check engine light ever comes on during low power let me know what codes you have you can use cruise switches to check for codes,if you don't know how to get codes let me know.
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