changed belts and...

ok, i just changed my alt. belt and my a/c comp. belt. Not as hard as i thought it would be...i started the car and it was shaking pretty badly and finally levelled out. it seems to be idleing around 500-600 rpm and when i rev the engine, on the way back to idle it dies.

now, my q is, do i need to adjust the timing or idle speed after changing these two belts? any info would be great....

justin
91 si hatch...stock

may have them too tight. Is it shaking with the ac on and off?