I have recently bought a BMW 316 I SE (2001).
The problem with it is that when i drive it, the engine oil will come out of the filter cap where i put the oil in.
I have taken it too a BMW dealership where they replaced the Camshaft Sensor.
I have also changed the oil filter but it still has the problem.
Another problem that I have noticed is that when im idling the car only has about 500 RPM and when driving it the engine will cut all power wont start afterwards.

The oil level isn't too high is it?

As it'll cause extra stress for the engine which might explain low idle, also the fact oil is coming out of the filler cap, if not is the seal around the filler cap still good, or is it broken, as oil systems are under pressure with the engine running causing it to leak out.