the belt may have stretched...new belts do that...if it ran good on the way home and doesnt now, im venturing tosay thats what it is, but get the codes read at autozone for free and then post it here before you do anything.
No - wasn't the belt stretching. Turned out to be the vacuum hose. My local garage fixed it for under $30 and didn't charge me for the code scanner either. Thanks for all the advice.