I am working on a friends 2003 6.0. The truck has 123,000 miles. The problem that it is having is that when accelerating from a stop it accelerates until it gets to about 3000 rpms. Then it feels like it has no power and won't shift. If I let off the accelerator pedal it will shift and then accelerate again to about 3000 rpms not shifting with the feeling of a loss of power. It will do this in all the gears. I just removed the turbo and did the cleaning procedures. I did the vgt relearn procedure following the cleaning. The truck has no codes.My friend said that he replaced both fuel filters about 6 months ago. Any help would be appreciated. Thanks

 

check the fuel pressure, check inlet restriction and if he used an aftermarket filter get new factory ones.
typicaly lack of shifting / delays in shifting are from a lack of fuel pressure. if that doent pan out start looking at things like base oil pressure, icp and ipr

 

The truck does not have any inlet restrictions. I will get both new fuel filters from ford and change them. I did a search for checking the fuel pressure but could not find it , does anyone know the procedure for checking the fuel pressure? thanks

 

if you dont know how to check fuel pressure, there is noway you would know how to correctly check inlet restriction.
inlet restriction is a vacuum test on the suction side of the pump.

 

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go to the dealer and get the new fuel pressure regulator kit.I just did mine last night and it fixed my problem.
Search my posts and see the problems i was having they are just like yours.

Get the kit or get a ball bearing that is .156 dia to .1875 dia remove cover on sec fuel filter remove the 4 screws pull spring insert ball and reinstall spring plat and fule lines that will also fix and itll be a cheap fix fi he wants to drop the 80.00 for the kit then he can once you fixed it with the ball bearing