I have a 2002 LB7 that has started to lose power. I can only get up to about 30mph going up hills and it takes forever to get to 65mph on the flat. When I accelerate, first gear is good then it shifts to second and the truck feels like someone is pushing on the breaks and black smoke pours out of the exaust. This truck has never smoked... and every gear does the same thing even neutral. If I get on it the same thing happens, it shifts down and then all power is lost. I have replaced the air cleaner but it appears from reading other posts that I should change the fuel filter. Any other advise?

 

I'd check the intercooler boots along with changing the fuel filter bud.

 

same as above, sounds like your losing boost.

 

cp3 could also be going out, but you would be throwing codes like crazy too if it was.

check the boots and also the intercooler pipe right where it goes above the steering gear box cause there can be a hole rubbed in it sometimes