I have been chasing an air leak on my 2001 LB7 for a couple weeks now and I still don't have solved. Its better but not good. If it sits for a couple days I can hear the air working through the injectors and it takes 20-30 seconds of cranking to get it to start. I have replaced all the fuel hoses on the engine, replaced the filter housing, found a small leak at the FICM and took care of that, blocked off the vacuum test port. I am thinking about shimming the pressure relief valve, maybe I am loosing some pressure there? Before I replaced the injectors 65000 miles ago, it started to crank longer than normal before starting and has been that way ever since. I considered that maybe the injectors are bypassing but, the balance rates look good. The worst one was 2.2. That wouldn't explain the air getting into the system either. Any ideas?