I have a 94 topkick with the 3116 cat. It has been slowly losing power over the last 6 months. now it is to the point where it has the power of a ford escort. I found a fuel line leak, noticed that the wastegate diaphram leaks pressure and the wastegate is siezed in an unknown position. The check valve on the return line in front of the engine looks new. I also found that the water pump was slipping because the belt was stretched. the engine temp never exceeded 200 and dont think that would have caused an issue. I was told that too much heat cracks the cups on the injectors ( I dont think thats an issue tho). I will be thankful for any and all help with this issue.

I'd fix what you already found wrong with it and that will probably fix your power problem.....

Iv fixed all but the wastegate. It is seized in an unknown position. I blocked off the pressure line to the wastegate valve. Is the wastegate to be closed at idle and open under pressure, or vise verse?
Ty

Iv fixed all but the wastegate. It is seized in an unknown position. I blocked off the pressure line to the wastegate valve. Is the wastegate to be closed at idle and open under pressure, or vise verse?
Ty

That's usually how they work..... If it's stuck open that would explain your complete lack of power...

Any blow-by?

None at all. U can take the oil fill cap off when running and u get 0 pressure or smoke even.

x2 on the wastegate