I have a 2002 WRX with 62k on the clock. I had the 60k service performed 3 weeks ago. I've noticed in the last week that the turbo boost is "spiking" when at full throttle. Regardless of gear, sometimes, when I go full throttle, the boost gauge goes to ~.11 MPa, then down to ~.09 MPa. Then back up to .11MPa and back down to .09 MPa. This contiues until I lift off the throttle. If I slowly apply pressure to the throttle until full throttle is reached, this does not occur, but sometimes it does, irregardless of the type of throttle application.
I'd like to diagnose this ASAP, so if anyone knows what I am experiencing I would really appreciate a response. Thanks.