what causes volt meter to act up.

What is your question?

when start car volt meter goes halfway for about 1-2min., then drops all the way down for about 7-8min. then goes back to normal reading. whats causing this problem?

What makes this problem better or worse?

it's like it lose power until voltmeter returns to normal. like nothings wrong

How long has your 2003 Pontiac Bonneville had this problem?

a few weeks