Hey,
I have a 2007 Volvo S40 2.4i with 154k miles. Recently it has developed a terrible idle especially when cold, coming to a stop, or while stopped at a light and letting off the brake. The whole car shakes and makes a very obnoxious bum bum bum noise and it seems like it's going to stall and urges forward. It doesn't matter if it is in park, reverse, neutral, or drive, the idle is still rough. It seems to go away while driving and runs completely normal. Yesterday after it stalled twice in a row on start up, I unplugged the MAF sensor and while it was unplugged the car seemed to run normal. I plugged it back in and the car ran completely normal until this afternoon. I appear to have no vacuum leaks. Has anyone had this problem or have any ideas on what it might be? I just replaced the MAF sensor with oem part, and have even used diagnostics tools to run tests and nothing is coming back relating to this issue. Thanks a lot.

 

I also have no codes, the MAF and throttle body was cleaned probably around 3k miles ago.