So long story short truck has a nv4500 swap from an 01 with an 02 motor that had the auto. Truck is extremely gutless until around 2000 rpms. Once you hit that it’s a completely different truck. Has an air dog that keeps 18psi fuel pressure. Have cleaned both iat and map. Can free rev all day but once you put a load in it there is a very noticeable lack of power. Checked codes and only codes I am getting are for the auto trans. 

Best chance is Dripley and those guys are more right about what is wrong, but I have to say the few things that come to mind in this situation.

Are you still on the old factory APPS or have you already changed over to the Timbo APPS?

How many miles on the injectors?

Is your turbo in good shape? No excessive play in the bearings causing rubbing or drag to the spin fins?

Do you have a clogged Cat in the exhaust?

@JAG1 I am going to assume it’s a factory apps. I did a reset and scanner shows 0%-100% 

again assuming but I’m betting factory injectors with 200k miles I’m them 

turbo is in good shape. No in or out up or down play. 

‘No cat or muffler from the 5 inch straight pipe.  

Sounds like it will be a great truck when running.

How about fuel related.......have you checked for clogged screens in the bottom of the tank module?

Run it with the fuel cap loose and see if the tank vent is clogged, it may be overcoming the tank vacuum at the higher rpms. I only experienced this on two trucks before when mine was visibly clogged and another fellow camper had fuel suction problems. Never seen it since those 2 times.

 

Ah never mind........ I see it's holding good fuel pressure.

Edited December 9, 20195 yr by JAG1

Most all sensors can be verified with live data tool. Like the APPS can be verified without replacing.