SLUGGISH, loss of power under load.

[OnlySonoma]

Hey everyone!

I have hit a wall! Not literally, but I have exhausted my knowledge.

I own a 1995 GMC Sonoma 4.3L TBI SLS

Symptoms:

The truck feels like there is resistance when accelerating.
Under a load it really bogs down and wont go up a big hill faster than 40 Km/ph. My fuel mileage has become absolutely terrible.

The engine will rev up when in park and neutral just fine.



I have replaced:

Fuel Filter
Fuel pressure regulator
Fuel Pump
Air filter
Spark Plugs
Spark plug wires
Distributor Cap and Rotor
PCV Valve
EGR Valve

I tried running it without the serpentine belt to see if a pulley wheel was seizing.



I will try replacing the injectors next.

I am not sure where the computer on this truck is located.

If anybody has any suggestions, I would really appreciate some help.

Thanks,

--OnlySonoma

 

[OnlySonoma]

UPDATE:

I seem to have fixed the problem but do not have an exact solution.

I pulled, cleaned, replaced, or inspected the following:
Throttle position sensor
Idle air control valve
Injectors
Engine coolant temp sensor
MAP sensor

What I think is the issue is the wiring harness.
It was pinched between the transmission dip stick and the engine block.
It was in bad condition and some wires were getting heated.
I tried to get it out from behind but cannot completely fix the issue as it is really wedged in there and i do not want to break the wires entirely. I believe that a wire was shorting out that controls the advanced timing so when i would give it more gas the engine wouldn't advance resulting in what seemed to be loss of power.

One thing to note is that the truck never stalled once during the 3 to 4 week period experiencing this problem. It misfires once or twice under heavy heavy load on a big hill when i gave it lots of gas.

I will keep the the post updated in a couple weeks to note if the problem returns.


--OnlySonoma