Hey scotty, love your videos.

I have recently bought a Ford Focus with the 1.6l ti-vct engine, the car has a freshly changed timing belt, oil, oil filter, and brake pads. Everything was fine till the cold weather hit (about 3 to-0 celisus).

It happens 90% of the time i have noticed, the car struggles to go into high rpm's (over 2500) and doesn't have the same power as before, also there's a deep humming sound from the engine at around 2500+ rpms, it sounds like the engine was sitting right next to me. The next symptom which is not consistent is going uphill right after a cold start, it sometimes happens that the rpm's are going up and down, after i press the brakes and take off again its working fine.

No lights on the dash, and no diagnostic codes.

Any idea what could be the cause of this?

Thank you for your response and have a nice day.