Trucks lacking power

[Justin e]

Have a 1998 k1500 with the 5.0 vortec, did a 230 mile drive last week with it and ever since the last 20 miles of the drive the truck has just felt sluggish and has needed to be given more throttle then usually to really get decent acceleration. Not sure if it’s converter related or air fuel related but it’s starting to drive me crazy. Motor is low mileage(47,***) too so a worn down engine is out of the picture. Any ideas?

 

[Komet]

Check fuel pressure, connect a scan tool and read some data.

 

[Schurkey]

Check fuel pressure, connect a scan tool and read some data.

And verify all the usual "tune-up" items--cap, rotor, plug wires, plugs, fuel filter, air filter. Check the PCV system, heated-air-intake system, EGR system, initial timing, electronic timing advance.

How old are the O2 sensors? They get lazy with age/miles.

Replacing the original "poppet" spider with the electronic injectors is a good idea, and allows easy replacement of the upper and lower intake gaskets.

 

[Justin e]

And verify all the usual "tune-up" items--cap, rotor, plug wires, plugs, fuel filter, air filter. Check the PCV system, heated-air-intake system, EGR system, initial timing, electronic timing advance.

How old are the O2 sensors? They get lazy with age/miles.

Replacing the original "poppet" spider with the electronic injectors is a good idea, and allows easy replacement of the upper and lower intake gaskets.

Most of the “tune up” have been done excluding fuel filter, been trying to avoid opening Pandora’s box with the rusty fuel lines. The intake upper and lower was resealed 6 months ago along with a mpfi conversion. Not sure if this might have something to do with it but the cat has begun to fall apart internally. And the 02 sensors are original. Will get out my scan tool and start digging in this weekend.

 

[WICruiser-97]

If the cat is falling apart it can easily plug the exhaust system creating back pressure and reducing power. Given it is already falling apart remove the cat and clean out the can so there is no restriction and see if that resolves the power loss.