Engine runs rough!

Hello Guys....got a strange problem....just put new plugs in my 01 740i, new air filter, and i have a rough idle....revving the engine to about 13-1500 rpms i have a vibration....had it scaned, no codes. Plugs are NGK. I added a can of BG44k and it seemed to be better for a little while but is rough again....had this problem for a while and noticed no change in gas mileage but now it is down from 18 CITY to about 14-15. Does this sound like it could be an injector? Will 02 sensors cause this? Out on the highway car seems to be smooth, but under a stress climbing a hill it seems to be a bit worse at around 45-50. I don't have any codes and the scans revealed NOTHING! YOUR THOUGHTS PLEASE??? THANKS FO MUCH FOR YOUR INPUT!

Rig injector clean and change fuel filter. Then we will go on from there.

RIG INJECTOR?? What does that mean? I am going to change the fuel filter this weekend....will let you know. How do you check the injectors or know if they are bad??? THANKS VERY MUCH!

BUT will injectors, fuel filters, or 02 sensors cause a reduction in gas mileage?