Hello everybody.I'm new here and I really need help don't know what to do anymore.I have the 2008 Duramax with about 120 something miles on.the other day I had the code p0087. I did change the fuel filter and didn't get better.I did change the fuel rail plug,the truck running a little better to about 55 mile and hour as soon you try to do 60 the quit and I have to get off and pry fuel filter 'once it gets pressure runs again for a wile and them quit and on and so on all over again .Can some help please.