OK folks, I've had +20K miles of trouble free operation since completion of the basic 6.0 mods ( head studs and gaskets, EGR delete, exhaust, SCT tuner). I used the truck (05 Excursion) last week to tow an equipment trailer with 9,000 lbs about 300 miles with no problems. After the 1st 150 miles, I disconnected the trailer and while sporting around town, noticed a pulsation in power only while under full throttle. I hooked up the equipment trailer yesterday and towed at highway speeds in the hills of NC with no problems. I have no DTC codes or other indicators (ex. air filter indicator) of problems. Any ideas on where to start with troubleshooting?