I have a 2006 chevy Duramax c5500 doesn't go over 2,000 RPM, when I clear the code P0087 it runs for about 5 minutes then the check engine light goes back on and does the same of not going over 2,000 RPM. I changed the fuel injector pump, cooling temperature sensor, change the fuel filter 3 times, and also the fuel pressure relief valve, fuel regulator. Additionally, I changed the fuel line and the returning line the two fuel levels to make sure the two tanks have diesel.
Still runs in limp mode. Any ideas?