Replaced upstream o2 sensor from top - removed PCV cover. Problem is gone.

I ended up replacing the VVT solenoid and also fuel pressure sensor without any change.
New observation: STFT switches to +40% everytime i go up any steeper hill.

Hi all, I´m dealing with an issue with my short term fuel trim (STFT) and therefore fuel economy also. The STFT switches to +40% and stays there until I ´´reset´´ it by driving without throttle for 5 or more seconds. Conditions that trigger +40% STFT: - Highway driving at 75mph or higher. I´m able t...