My 2013 truck seems to have developed a misfire I think, It will not pull smoothly through 3000-4000rpms, and its even worse while pulling our 7000lbs TT and also whilst towing the boat (4000lbs)

Has anyone else suffered this or something similar?

The truck is 2013 model year and just a year old and has about 24000 Kms (15000 miles)

 

May be a loose sparkplug?????? Any codes?

 

So, it seems that I had a faulty fuel pump.... pretty rare apparently