98 k1500 5.7 stumble on light acceleration

[Lodogg2221]

My 98 K1500 5.7 has an odd stumble/miss on light acceleration.
It idles fine, and if you accelerate harder, it will run great, and full throttle is great too...
Any idea on what it could be? IAC maybe?
Also once it warms up good, about 20 min of driving it seems to go away...or at least it did today.
Dont know if it matters, but 167000 miles.

I had zero trouble out of it till now, I mean its always ran great.
It does have a 10 month old tune up, plugs wires, cap, rotor...
Newer fuel pump, about 2 years ago, which even if it wasnt new, would be more of a problem on full throttle high rpm, which it isnt...

I guess I should add, no check engine light when it does it.

[J-Ri]

Most likely not the IAC.

I would try a good fuel injector cleaner (Like SeaFoam or 44k). If it only does it cold, poor fuel evaporation from bad spray pattern is a possibility. Did it start doing this after the weather got colder?

[Lodogg2221]

No, it actually started it when it warmed up. Lots of condensation on everything, sidewalks, etc...
Anyway, I thought maybe it was a fluke, but its not, still does it. I guess the odd thing is no check engine light...
Ill try the fuel system cleaner, and see what happens. I ran some thru a while back, so I wouldnt think thats it, but I have no ideas....

[5150Watts]

Im currious on this myself. My 97 5.0 just started doing this. Also, mine feels like the acceleration is lacking in get up and go too.

[Lodogg2221]

Ran some Lucas Oil Fuel system treatment and everything seems fine now, hasnt done it in the last few days...

[j cAT]

Originally Posted by Lodogg2221

Ran some Lucas Oil Fuel system treatment and everything seems fine now, hasnt done it in the last few days...

some have found though cleaning of throttle body stopped surging/ stuttering when maintaining a constant speed.