Turbo will not spool or will die if you loose fuel. I would bet you are loosing fuel for some reason. If it was the turbo, it would smoke when you lost boost.

 

How do I "loose" fuel? I don't understand the term

 

For some reason the engine is most likely defueling due to a mechanical or electronic problem. I dont know the in's and out's of the failure codes and limp mode for cummins, but most engines will do this when there is something wrong or it "thinks" there is. The idea is to let the engine run until you can get it somewhere and get it fixed, but not run at full power.

 

it sound like you might have a few things that could be bad. apps or bad VP-44 dead or dieing LP. the turbo only responds to the heat going though it (fuel)if it spins free its probably fine if the lift pump is bad it will ruin the VP. pull the codes again if you get p0216 its not good get someone to test the lift pump and put a in cab fuel pres.gauge in it or at least a low pres. light intermittent power drop off sounds like the VP44. i just installed a new VP on my 01 SO that had real close to the same poblem your having. hope this helps.

 

The lift pump was just replaced and the problem existed before the new transfer pump and still follows the same pattern, fine once warmed up but the problem occurs until warm. The VP44 is about 3 years old and when it went out the first time it was because of a dead transfer pump. Even then, this kind of problem didn't happen. Also, I not getting a check engine light so I don't know if any codes are even going to be present. Cummins told me over the phone it was probably a wastegate issue but I'd like to know before I pay them $95 an hour to find the problem.