My 04 Taurus 3.0 vulcan, 98k mi, had a CEL turn on and I took it in to autozone and got The lean codes P0171 and P0174 as well as P0420 and P0430 which are both cat efficiency for each bank. The guy there thinks its a vacuum leak or MAF sensor. I just bought the car and the guy said he changed the spark plugs and wires less than 30 days ago. The car started running bad at idle and basically feeling like it is going to stall out at red lights. When I give it some gas it seems to run fine, with no noticeable loss of power and cruises just fine. It's only at idle that the RPM's drop to 600-800. When I cold start the car the RPM's jump up to about 2000 and sit there for a bit and then drop to 1000 and then lower and the sputtering starts. I was wondering if this has happened to anybody and also if I should even drive it the couple miles to the auto parts store or if it is risking melting something.