Hesitation then loss of power after 20 minutes of driving
 

Hey guys ! I have an '05 S40 T5 and when acclerating fairly hard after driving about 20 minutes the car hesitates and becomes very sluggish as if the turbo is not spooling. It will still run smooth, just very sluggish and if I restart the engine it is fine until I accelerate fairly hard again. There has never been a check engine light on and the issue did not occur until I changed the oil (coincidence ? ).

Anyone ever had this issue or have a clue what I can look for ?