Have a 2003 6.6 Duramax, and when I step into the fuel pedal to make it down shift into passing gear, it does downshift, but then the fuel pedal goes dead, it will not rev higher than 2000 rpm, and if I hold it down, it brings up code P00087, Fuel Rail System Pressure Too Low, and will smoke until we let up. This problem has been dogging this truck for just about a year. The dealership replaced all injectors, fuel pump, countless fuel filters, fuel tank, all new fuel lines (except for the fuel cooler rad on the frame), and now, tonight, we changed the fuel temperature sensor. No change! We are at a loss here. Hoping someone out there has an idea on what might be causing our headaches. Am posting this for a friend, and until this year, this truck has been bulletproof.