94 3406E to 06 C15 Acert

Hello. I just did this swap, finally got all codes cleared but now she has very weak hill power loaded. It seems as though it only has half the usable throttle under load yet Will tach out at over 2000 rpm just sitting. I'm out of ideas short of advancing the fuel and timing. Any ideas? Thank you much in advance.

 

Grenades an air compressor and road service didn't change the oil after fix so it smoked the block and crank. I had the newer motor just sitting here...so I shoved it in, with a bit of persuading. Like I stated, only code I'm getting is "55"..."all clear". Everything is original from truck right out to end of engine harness.

 

Yes. It had plenty of power. 550 hp if I was told correctly.
I haven't checked the boost pressure yet, ive been hoping getting the codes to clear would help. Fuel pressurw is fine.
Yes. I'm using the TPS from the truck. As I said, the only difference is the motor, all else is the same. I'm basically running the new motor just like a 3406E. Original ECM as well.