Over heating!

Ok gents. I will start off by saying that I have changed the cooling system in the car already and am now starting to have this problem...When in idle, my car begins to overheat and as soon as I begin to move again it goes back to normal. I am baffled. I bled the lines to see if there may have been air in there and it seemed to fix the problem temporarily for like 2 weeks....now it's back.

Any ideas? Suggestions?

Check to see if the electric fan(s) still spin freely and function properly. They help with cooling when car is stationary.
Good luck
Fun clutch is working properly, replacing electrical fan as it is intermittent. HOPEFULLY this fixes it. There seems to be air in the lines so I am worried it may be something bigger.
The aux fan (electrical) does not come on unless you have the AC on. The fan clutch should keep her cool at an idle. If you have air in the coolant that is the problem and the symptom of something bigger if it keeps coming back.
Yeah it was something much bigger...3k bigger. So, I gave the car to my dad to use for parts for his 98 528i and am buying a 2008 Mini Cooper S with everything. I know. Cooper from 5-series...but it's still a BMW product.