Haunted 1997 5.7 vortec

[MyBrokenChevy]

Good afternoon everyone. Allow me to introduce my wood truck "Becky."

You must be registered for see images attach

Becky is a 1997 GMC SIERRA 2500
I have used this truck for gathering firewood to heat my home. At the end of last year Becky started choking out under acceleration. This problem started out as an occasional flare up and has became debilitating to the truck.
There are no codes displayed and yes my check engine light isn't burnt out. After doing some light research I found the problem I'm having could be a number of parts. Logically I just figured throw enough money at it and it will work again right? Wrong.
Since last December I've changed the following.
Fuel pump
Fuel filter
Fuel pressure regulator
Intake gaskets
Throttle position sensor
EGR valve
Coolant temp sensor
O2 sensors
Camshaft retard sensor
Mas airflow sensor
New ignition coil
Cap and rotor
Plugs and wires
And finally I cut the cat off hoping it was plugged
It was melted together but the truck still ran poorly after it's removal.
And after all that she still runs like ****. Needing to heat my home I posted the truck for sale to purchase a new wood truck. That is when the original owner of the truck reached out to me and informed me he installed a new engine with a RV cam when the truck had 190,000 miles. The truck currently has 230,000 miles. With this newfound information I would love to get this truck back up and operational. I would appreciate any insight you may have as to getting this truck back to heating my home.

 

[SAATR]

Get a diagnostic tool capable of reading live data, and a fuel pressure gauge. Need to know the following information, with the engine idling at operating temp:

Idle speed and desired/commanded idle speed
Fuel pressure
Coolant temperature
Inlet air temperature
MAF flow
manifold pressure
Spark advance
Short term fuel trim (STFT) and long term fuel trim (LTFT) for both banks
Throttle position

And we'll go from there.

 

[Teddygraham]

I had a similar issue with a 98 4.3. It was the coolant temp sensor going bad and creating an open circuit intermittently.

As stated, live data is essential

 

[1998_K1500_Sub]

And finally I cut the cat off hoping it was plugged
It was melted together but the truck still ran poorly after it's removal.

Hmm... assuming the cat wasn't plugged when the prior owner installed the new engine, what might have caused it to plug since?

Mixture too rich?

I'm trying to work backward from "What caused the cat to plug?" to "What might be wrong here?" I'm coming up blank. Help, anyone?

Get a diagnostic tool capable of reading live data ... Need to know the following information, with the engine idling at operating temp:

(LIST OF PARAMETERS)

Might want to add "Knock retard" to the list. Knock retard under no load and under modest load should hopefully be zero or close to it.

 

[1998_K1500_Sub]

There are no codes displayed and yes my check engine light isn't burnt out.

Did you read the codes anyway? Sometimes a "pending" or "stored" code might be resident that didn't set the SEL, so checking never hurts.

 

[MyBrokenChevy]

Hmm... assuming the cat wasn't plugged when the prior owner installed the new engine, what might have caused it to plug since?

Mixture too rich?

I'm trying to work backward from "What caused the cat to plug?" to "What might be wrong here?" I'm coming up blank. Help, anyone?



Might want to add "Knock retard" to the list. Knock retard under no load and under modest load should hopefully be zero or close to it.

It was running lean for the longest time, so we would run the truck in open loop by unplugging the maf sensor this kept the truck running good enough to collect firewood. But the truck would crack manifolds from how hot they would get

 

[MyBrokenChevy]

Did you read the codes anyway? Sometimes a "pending" or "stored" code might be resident that didn't set the SEL, so checking never hurts.

Absolutely no codes I hooked a scanner up in hopes of a "background code" but there was nothing.