Wife's 2001 Altima is at it again. It now has a rough, low idle and has codes of P0505, P1490, P0446 and P0325. I am hoping that all the codes are associated and a single fix will cure them all, but not sure where to start first. Car has 170,000 miles and runs good on the road, it is the idle that is a mess. I don't find any obvious vacuum leaks and was wondering if anyone could lend a hand.