4.3 v6 GMC Sierra issue 2004

[Humberto Alvarez]

I have a 2004 GMC Sierra 4.3 and lately it's been like losing power when I'm driving down the road it acts as if it stalls and I pump the gas pedal and it turns back on or regains power. I have replaced the fuel filter, fuel pump, speed sensor, mass airflow sensor, spark plugs and also cleaned the throttle body. Do y'all  have any idea what could be causing my truck to be acting like that?

[Jworks]

Catalytic converter stopped up is a possibility.  I had that issue on a '94 GMC with a 4.3 engine.  In my case it would crank up, run, then give it the gas and get to about 20mph tops; and sometimes just die.  Not cheap to fix if thats the issue.  There are people that can do a flow test on your CC to see if its stopped up.  I would try to find someone you can trust because most of us don't know a thing about the flow rate.

[Humberto Alvarez]

I forgot to mention I got the Catalytic converters replaced 2 months ago, like you said I experienced similar side effects so I got them replaced and turns out it was the problem, they even took out to pieces out the exhaust. Anyways, it was good for awhile but started doing the same thing again so I'm thinking its something else now but cant seem to find the problem. Makes it harder that no check engine comes on to at least point in the right direction of the problem. any other ideas? 

Edited September 18, 2021 by Humberto Alvarez
forgot to add something

[Jworks]

Wow, that is odd.  It quit acting up after you replaced the CCs....but then went back to doing it again.  The same exact thing??  That is odd.  I hate to say take it to a dealer...or at least a good mechanic if you know one that is real good and can trust.  Thats what I would do.  Fortunately, I have both a good independent mechanic and a good and honest dealership that won't jerk me around.  I'm wondering about the gasoline you're using.  But...I think even the off brands would not do that.

 

Edited September 20, 2021 by Jworks