At the moment, I check for faults before starting the car. Every day, no errors, turn the key and starts the engine, and the "Pressure drop error" is displayed... I let it idle for 20 sec... clear the fault and check for errors again... no faults will then be displayed... if I then stops and starts the engine again...still no errors....
 
You can says is always the "first timer" that makes "pressure drop error"...each morning... when i'm going from work 8 hours later nothing happens... could seem like it's related to the temperature...
 
From my experience the pressure drop is a common fault for a few things. You have changed all the obvious items except the n75 which has caused people various problems in the past from limp mode to bouncing boost.