E61 520D revs by itself!

[amdre02]

Hi everyone. Sorry in advance for long post, and for my rusty english.
I own an e61 520d automatic with the n47 engine, which out of nowhere got the weirdest problem.
One morning when i started i noticed that the idle was high, it usually runs at 1000rpms, but that morning it was at 13-1400 and wouldnt drop. When driving its as if i got cruise control activated at all times, it wont drop under the speed i go at even if i let go of the accellerator for 10-15 minutes. It also refuses to drop under 1500 rpms, even at speeds of 90-100 km/h.
This happened about a week ago, and haven’t changed yet. I am at a complete loss of what to begin searching for.
Today it also began accelerating by itself, from 1500 to 2000 rpms without me touching the pedal.
This is beginning to really bug me, do y’all think it is an engine related problem (turbo, injectors etc) or more a case of the transmission locking up or something along these lines?
Any any help at all is appreciated, this is driving me mad.
/André