idle issue continues

so a month ago i changed the vanos since my car was giving cold start issues even in warm temperatures. once i replaced with dr vanos rebuild, the cold start idle jolts and stalls stopped however i saw no difference in performance and the diesel vanos rattle was still there even after the replacement. so the noise didn't disappear. now a month and a half later the weather is cold and i noticed one day after the car ran out of gas completely eventually leading it to stall, once i refilled the gas up full tank, the car will had ONE idle hiccup when its really cold once in a while. it even stalled on me. is it possibly the fuel filter sucked up the dirt from the gas tank and causing cold start issues again or can it be possible for the vanos replacement to be failure since the vanos/diesel rattle noise never left...any help would be appreciated