Just wanted to spread the info. I've been fighting a surging problem with the 3L SVT Contour I built for my wife a year ago. It hasn't been a major issue so I haven't had to fix it right away. The surging basically happens only when the car is crusing. Nothing horrible but you can feel it and it gets annoying. It ran fine at idle and wide open throttle (WOT). I talked to a friend recently and he said his DPFE sensor was causing the problem with his lightning. He said if you unplug the sensor the surging should go away if that is the problem. If that fixes then you have to buy a new DPFE sensor and replace the bad one. I found out that the DPFE sensor is NOT monitoring the EGR gases at idle or WOT so now it makes perfect sense. It is only working when cursing or at half throttle. I tried unplugging the sensor and after a few minutes the surging went away. For anyone having this exact issue: "Surging only at crusing speeds" I recommend unplugging the DPFE sensor to see if this fixes it. If that's the cause look for a new one. Hope this helps someone.