I have a 2001 S60 T5 has been running fine until yesterday, I was coming home, about 50mph and car lost some power and could feel a vibration in the steering wheel. This has nothing to do with the tires or wheels. I got the car home, looked under the hood, nothing obvious, serpentine belt intact no leaks. Thought maybe it was a bad plug, pulled them, noticed one was not quite hand tight(loose) and the wall was dirty, pulled the plug, was oily. all others clean. I had had the plugs changed in a while so I installed some NGK iridium plugs, hoping, praying that this was the answer. NOPE new plugs in, still vibrates when the vehicle is turned on. Anything you guys can think to llok at before it heads to the dealer for a repair that will cost more money than its worth? The car is running the IPD exhaust,IPD ECU upgrade just as an FYI dont think that this is relevant to the problem. Thank you

 

Try cleaning the throttle body.

 

clean them with what? Dont even know where they are. This could cause the engine surging at idle? And come on all of the sudden?

 

Yes it can the throttle body is under the intake manifold.
You can use Brake cleaner to clean the throttle body.

 

Might Need to replace the Oil Trap, and there's a bolt on the bottom of the Intake with a Hole that leads to the Oil Trap which can get clogged up.

Also did you get any messages like "Reduced Engine Performance"?