2000 Lumina 3.1 Lights dim, tach jumps, often needs to be jumped

[Tuco1369]

I have a 2000 Lumina 3.1 I often (half the time) need to get a jump start. While it's running, the tach jumps/bounces around even though the rpms seem to remain the same. Also the Lights get dim and bright while driving.

It is not the battery or the alternator because both were just replaced.

Any idea what this could be?

Thanks
Tuco

[Tuco1369]

Uh oh! The lack of responses to this scares me!
If you guys don't know the answer, no one will!

[maxwedge]

Surpised no come back on this, Check the alt. output fully loaded, make sure all the grounds and positive cable connections are clean and tight.