I've got a stock (160k engine/trans) 97 12v auto. KDP killed, gauges installed. Everything seemed to be running good as long as I don't put my foot in it. When I do I get a horrible bogging sound.
Just the other day I had to move a small load of round bales (15k pounds). Any time I had to push the pedal down there was no power! Boost, pyro, fuel pressure, oil pressure, and engine temp all look good.
Once out on the highway, if I hit any incline there was hardly any power to move. The pedal has a horrible vibration, and is very stiff.
Any ideas?

 

Low fuel pressure due to clogged filter(s) or a bad overflow valve.

 

What is the fuel pressure?

 

New Fuel filter, new overflow valve, Fuel pressure runs 24-26 idle and can reach 32 at WOT.

 

Doesnt really sound like low FP.

How long have you had this truck?

 

About 6 months.

 

What i meant was - has it had low power since youve had it or has it lost power all of a sudden??

Accurate info really helps here.

 

Low power since I've had it.

 

Ok, Im not sure what you are expecting in terms of HP as well, 15k pounds is not really a small load.

In stock form, 12Vs do not have a lot of power. A 97 auto has a 180 p pump and will likely dyno less than 100 hp at the rear wheel.

You could look at doing some performance mods. Maybe a #10 plate and 3000 gsk springs (although your tranny may not like it too much).