I had this one for a while on my 2000 Taurus and there's no real damage to the engine it just inhibits power and cuts down on mpg a bit if not taken care of because the engine will try to compensate for the lean codes. There's a few things to check on this. Oxygen sensors, EGR system, Mass Air Flow sensor, check for dirty or clogged air filter which can clog up the MAF. You can clean that out with some brake cleaner just be sure the MAF is dry before you reinstall it. Check the vacuum hoses for any leaks or breaks. Check the fuel filter and that you're getting proper fuel pressure. You can pick up a gauge for that at a local parts store and if they don't have one they can order it for you. You can also try running an engine cleaner in case there is a dirty injector or just some gunk that's clogging something. Worst case scenario, which ended up being the cause of mine, is a catalytic converter. Those you can get a direct fit or a universal one but you have to have pipe to modify to put a universal one in. There's a few wholesale autopart websites you can order one from for $200-$300. Otherwise Ford will try to get you to pay $300-$400 for one of theirs. Mine had two so thankfully only one had to be replaced. If you can find a mechanic to cut it out, they can clean it but most shops won't do that because it's a temporary fix and won't pass inspection and they can't guarantee it will keep the check engine light off but for a quick fix to replace later they can clean it out and weld it back in. I haven't found many mechanics who will do that though. Check the small inexpensive stuff first before you go to a shop so they know what not to check. And for some prebent vacuum hoses you can actually go buy a unicoil at O'Reily's and bend a straight hose up to 90 degrees without it pinching. Can help save a dollar or two here and there.