multiple miss fireing when towing

I have a 2001 2500hd 4x4 crew cab.when i tow my 5-th wheel i get a noticeable skip or miss fire but it only is felt when i have a load behind it.today my mechanic cleaned the injectors.this weekend i am going to tow a 20-ton backhoe to the lake to clear land i hope it does better.any sugestions are appreciated. Thanks Big Daddy

I have a 2001 2500hd 4x4 crew cab.when i tow my 5-th wheel i get a noticeable skip or miss fire but it only is felt when i have a load behind it.today my mechanic cleaned the injectors.this weekend i am going to tow a 20-ton backhoe to the lake to clear land i hope it does better.any sugestions are appreciated. Thanks Big Daddy
I went through that 2years ago, have the injectors cleaned

Norm

Mine would miss under load. I neglected to replace the wires
when I did a tune. When I replaced the wires, prob went away