my 03 6l was out on the weekend pulling. i tow a 8500# 5 th wheel with around a 3000# boat behind it. the total length is around 75 ft. anyways things were going good and then after passing a vehicle when i let off the throttle the truck felt like it was bucking. once you hit the throttle it pulls not bad. after we got to where we were going i unhhooked and took the truck out on the road. by doing a stall the truck would seem alright but maybe a little low in power. once i took my foot off the pedal and let her rip it would buck while accelerating with lots of smoke and low power. i checked for codes and i had p401,p603 and p132. i have a egr delete and a bd xtuner which i was running on the 5 power setting.i believe the 401 is because i have no egr the 603 is from the tune thats in the truck but cant find any info on the 132. when i clear them and drive i get the 132 . no cel comes on but they aRE being logged . anythoughts or ideas would help.