So for a couple of months now my car has been running pretty weird at idle. There are a few things that sometimes happen. At times, it starts at a low idle, then almost stalls out and then proceeds to idle normal. Other times, it will just stall out right from the low idle. And the last thing that happens sometimes is it starts to idle sort of normally but then when it goes down to a low idle after a cold start, it bobs up and down from about 250 rpms to almost 1,000, when a regular idle sits around 1,250 or so. However when this happens, if I even tap the gas, it revs up and falls at a normal idle perfectly. I've got the engine code P0171 which is system too lean (bank 1) about twice in the past month or so, and was just curious if this had anything to do with the consistent weird idle. Only engine mod I have is a cold air intake, and I can't find any vacuum lines that aren't connected. It's safe to say that when it's cold, it never starts up and idles normally on it's own. Any help is much appreciated!
Thanks

 

What Mazda 3 do you have? BK? BL? BM?

Throttle cable or Fly By Wire?

 

BK, 2006 with a 2.3. I believe it's electronic fly by wire.