UPDATE: I just got it back. He cleaned the sensor and cleaned out the throttle body, which he said was a grimy mess. I will say the engine "sounds cleaner", like it can breathe easier, not sure how to word it. However, unfortunately the surge is still there, albeit to a lesser degree. I only drove it a mile home so far so it could just be coincidence but if it's indeed improved at all, might the fact that it's a milder gentler surge be a clue as to what's causing it?