About a month and a half ago, I was driving home from a date, when my 2000 Mustang V6 convertible started losing power, spitting and sputtering. I didn't know what happened. Well, I was almost home, so I nursed it in, and the next day I called a wrecker. I sent it to my mechanic, and he put plug wires and new plugs on it and declared it repaired. He also replaced a squeaking tension idler, which was definitely bad, but I was skeptical about the engine repair. First of all, by the way it failed, that just didn't sound right. But I paid him and went on my merry way and for a day or two, it ran OK. But then it started acting up again. However, instead of sending it back to the mechanic, I decided to put my old Auto Xray code reader on it and see what it came up with. And it did come up with something revealing. It read: TP sensor not consistent with MAF sensor. So, I had a direction to go in. So I removed the air cleaner assembly and found that the screen in front of the MAF sensor was punched out. Half of it was still attached. Now I'm thinking, I wonder how that happened? Did that disturb the air flow so much that it threw off the MAF sensor reading? I read on the internet about someone who had removed the screen and found out the engine wouldn't idle right with it out. So, I thought, maybe so. Well, I couldn't figure out where to get one of those screens, nobody lists it, I finally found it on Ebay. So, I ordered it, and today, I installed it. But what I discovered when I went to put the air filter housing back in, is why the screen was punched out. The old air filter was missing that plastic cone at the end that caps the filter and keeps unfiltered air from getting in. It had broken loose and got sucked into the MAF sensor housing and punched out the screen. In that place, it was a major restriction to the air flow going into the MAF sensor and the intake itself, since it was almost as big as the intake pipe. But it would shift position, and allow the engine to run sometimes, and not at others. Very confusing. While I replaced the filter with the same type of filter that caused the problem, I intend to change that out for a K&N filter that has a different kind of cap that can't be sucked in because it straddles the end of the filter. Besides, I understand it's washable and reusable, so it would certainly be worth any extra cost. Dampness may have been a contributing factor to the failure of the old one. Had I taken it back to the mechanic, he probably would have missed the root cause of the problem, the detached cone, because when I pulled out the air cleaner assembly, it fell into the area below the air cleaner and would not have been noticeable.