I recently got an old 2009 w204 c220 cdi 170hp manual with about 200k km, it initially came with a hole in the intercooler tube, some burnt cabling around the fuel injectors and one of the injectors has been recycled or whatever the word is in english, but everything has been fixed and replaced in the car and its as fresh as new.
Problem is when starting the car after half a day of sitting, even in 20-30 C° weather it starts revving up on random until it warms up to 60+, it initially stays at about normal idle rpm then jumps to 1.1k-1.3k at random intervals and at random strengths, its sometimes a 100rpm jump and sometimes 500. Ive looked around google and some say its a missfire, some say its idle hunting and some say its normal when cold so i dont know what to do.