Voltage fluctuation problem

[beejay]

I have a 00 Tahoe, 5.3. I recently started noticing that my voltage needle is flickering a bit while idling and more so while driving. While idling, when I give it gas, the needle will drop significantly, lights will dim and truck will want to stall then go back to flickering again. Same thing while driving, the needle will flicker and as soon as I step on accelerator hard, it will drop and climb back up and flicker again. Here's what I've looked at and done so far,

1.) Checked and wiggled all connections and ground
2.) Alternator was tested and tested out fine, also have a new battery
3.) Changed the whole main tensioner assembly and belt
4.) Cleaned battery terminals and checked connections

None of the above have solved the problem

Is there anything else I can check myself or tests I can do? I'd rather try to fix this problem on my own before having to take to the shop.
Thanks!

 

[Voodoo]

Check your grounds. The one coming off the starter and others that will attach to the body etc.....

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[YukonXLPerk]

Have you taken the grounds off and then cleaned them up?
While it is off, take a good wire brush and make sure it is real clean. Put it all back together and give it a good coat of paint to keep the surface rust off.

 

[beejay]

Had already did what two previous members suggested. I changed the whole main tensioner pulley assembly, new belt and just recently replaced the alternator because there was a part inside that was found to be defective. The fluctuation went away now it seems that right before I make a stop or accelerating after the stop my voltage gauge will dip to about 10, lights will get dim and then go back to normal. I can't figure this out for the life of me?????

 

[middelgriff1]

Try cleaning your throttle body. I was just researching this yesterday and apparently a dirty tb will cause this in our trucks. Gonna do mine this weekend