As I have mentioned offline the tune is the likely suspect based on what symptoms you have relayed to me. Mechanical issue is the least likely and as others have said the surging is not something to be worried about especially during little throttle blips or light load. Without datalogs or really any real information it's pure speculation. James I believe said the same thing I did when you first contacted me. It sounds like an injector scaling issue or perbaps something else in the tune that is a little off. I'm not usually so quick to suspect the tune but in this particular case it's something that needs evaluation. I will leave it up to the OP to disclose who is/was tuning it but really I feel you need to find someone else
