So today I was up in the snow wheeling in my 01 5.4 screw, and it has done this before, but after about 4-5 hours of making it work in the snow there was about a 20 minute period where i was super bogged down, couldnt get it over 1500 rpms in gear and it wouldnt even turn my wheels pinned in about 2-3 feet of snow. what could this be? a few variables to consider, higher altitude, 162k miles on OG tranny and OG motor.

 

Snow in the intake. Especially if you were around a lot of powder. I had this yesterday while plowing. My entire intake had an inch of snow around the whole filter, and pinned it would only go 40 km/h. Reach in an check the filter, and if you did the gotts mod, you can reach your hand down the intake into the fender and see if there is a build up of snow in there too. Quick overnight in a warm garage will fix it.

 

Could it be clogged Catalytic Converters?