When I first installed my Westach FP guage I had 14 at idle and would not fall below 10 when cruising. I changed FF after FP guage install and pressure dropped by 2lbs. Now at idle I see 12 but can drag it down to 6 while pulling trailer. Is there just air in line or am I seeing lift pump slowly dieing? No codes and truck seems to run fine. Truck is stock other than what you see below.