thank you guys. I forgot to mention, as soos as i give it gas (even barely) sound goes away. She becomes smooth. No knocking, etc. While driving. No hesitation. Driveability is smooth as usual. She has 55k on her now.

Do you guys think winters brutual cold weather caused this? This happened in the middle of winter. I suspected that, my gf drove her while the engine was ice cold, went kept the rpms a bit high. What do you think?