I have a 1999 Ford F-250 Super Duty 7.3L. The problem I'm having is that as we approach winter and the nights get colder, my vehicle is accelerating very slowly. For example, if I'm going down the road, a fairly loud "fffffffffffff" noise can be heard coming from the passenger side of the engine. It also accelerates very slowly and won't really go above 30mph. After like 10 - 15mins of driving/running the vehicle will get a boost of power allowing me to get up to speed. However, the noise from the engine is still present but not as loud.
I've been told that it could be a turbo vacuum leak but I'm not sure if that's the case or how to check for that. Any help would be much appreciated.
Thank you for your time!