Ok, I've got a 2007 F150 5.4l 4x4. Last year had the cam phasers, timing, VCT's and spark plugs done. Has been running fine. Drove to work a few days ago no problem but when I went to leave, noticed a put-put kinda sound just happened. Almost like a diesel sound a few people say. Does not go away with temperature and stays right in sync with the rpms. Definitely coming from back of engine passenger side. Along with that is a strong exhaust smell and terrible gas mileage. And P0420 and P0430 codes both. Have checked and checked (still checking currently) for a leak but no luck. Alot of people say the cats are bad but the way it just sprang up all of a sudden kinda led me to believe it might be electrical or just need to keep searching for a leak. Dont know. Any help appreciated