Have you tryed to remove de exhaust pipe it may be clogged I ran a straight pipe for now but my engine blew after 14 years of hard work

 

pop your upstream o2 sensor. if it's a bad cat / exhaust, you should tell a difference.

 

Any message come up in the driver information center? Did it say reduced power mode? Traction control fault? Check stability system? Is the check engine light lit? Reduced engine power will cause the truck to go into limp mode. This can be caused by several different things. Most notable are throttle position sensor going bad on the throttle body. Bad MAF sensor. Or a dirty throttle body. The engine computer compares the readings it gets from the MAF sensor the throttle position sensor on the throttle body and the manifold absolute pressure sensor as well as the intake air temperature which is inside the MAF sensor. If a wire is broken that sends a signal from any of these sensors to the engine computer it will cause the truck to go into limp mode. Also the wheel speed sensors can contribute to the problem. If you code scan the truck look for code P0068 or P0101. This indicates a problem with the computer correlating the throttle butterfly valve correctly to the amount of air entering the throttle body. It all has to do with the optimum air fuel mixture. Get your truck scanned for codes.