I have an Xcal2 w/ a tow, street and extreme tune from Lund Racing. I have a built tranny with a Sun Coast converter and parts. Have any of you guys ever encountered what I would call a surging problem with any of the extreme tunes. My tuner says he has never had any problems unless injectors were changed or fuel system modified, my are still stock. He also said Ford had a reflash for 03 and 05-07 6.0's to fix MPG and surging problems. I haven't had a reflash that I know of. He says the could be caused by the ICP pressure switch which he claims is rescaled and highly altered. He said "Just about ever Diesel issue I have encountered is led to bad ICP sensor and or a Bad EBP sensor." My truck only does this under WOT and only on the extreme tune. Thanks for any help you guys can give.