I have a 2008 3500 with H&S Exhaust delete installed for the past 7 years with no problems running at the "wild" setting. My truck recently is showing trouble codes P1011 and P0087. I replaced the fuel filter first which didn't help. I then dropped the fuel tank and replaced the pump. The codes reappeared when accelerating with a trailer. Any suggestions on what to do next?

Thanks,
Jules