ok last week i installed a new head gasket then put the truck back together and started it. the truck sounded like crap and was blowing diesel out of the first hole in the driver side valve cover. so i tighten it and it stopped leaking. it was still running like crap then i realized i forgot to plug in a sensor. ( it looks like a fuel distribution block on the driver side which is secured by 2 nuts.) i pluged it in and it sounded alot better but was still bad. i changed out the oil because i had diesel in it. i checked the codes and p0088 and p0090 were coming up. the truck will not go over 2000 rpm's. if i start it and floor it right away i will go over 2000 rpm's but then i guess when the computer realize's the codes then it will not let it go over 2000. i dont know what to do i did not mess with anything to do with the fuel besides diconnect lines and thats it. i wonder if i replace the sensor if it will help. i just dont know why it wont go over 2000

thanks louis

The fuel rail press regulator is on the juction block, which is probably what you left unplugged. Check to see if there is pwr and gnd when running. You may have to clear the code to get it to run better and if the code doesn't reset.
good luck..

i cleared the codes a million times but i did not check the hot or ground

DTC P0090 is a current flow problem in the FRP regulator circuit. This incorrect current draw could lead to incorrect fuel pressure. This DTC is set when FRP regulator circuit current is not between 50-1,600 mA.

DTC P0088= actual fuel pressure is more than 167 MPa, which could be caused by the incorrect current draw indicated by the DTC P0090.

ok truck is fixed . it was a cut wired and repaired it and it runs perfect.