drivers side knocking, but weird...

[Julian1989]

hello, audi a4 b7 2005 2.0 tdi, BLB, changed cambelt water pump, oil, diesel filter, and the battery with a 71 amp one  the previous owner had a 62, anyway, sometimes the car engine starts at the first rev of the crank, other and most often after o e second and a half ish, no weird sound as far as I can tel yet, but, at idle, the needle stays within the 850-900rpm range, the car intermittently shakes, and the mother of knocking starts exactly in front of me,  tracking it, leads to the brake booster, but I can hear it inside the metal pan like cover..., when I touch the gas slightly, it goes away and all is good,  when stationary, if I rev it between 1800, 2000, rpm, its not there, but when I drive, and hit the 1,8k 2k rpm, it stays untill 2.1k rpm, ah I almost forgot, when stationary, when turning the steering wheel, feels like it's vibrating somehow, like it's rubbing against a sprocket,  can't seem to notice it when driving... 

any ideas?