Acceleration failure at Fiesta Fiesta XR2I

Hello, it happens to me that when I accelerate suddenly I start to fail and head, I do not stop or anything, but it fails as if it worked in 3 cylinders, but in the morning when I turn it on it works well, there it starts to fail and out there, a year ago I had to lower the gas tank because it had some stones as if they were crystallized naphthaline Tremendous, I remain well, but out there this fault comes, I don't know if it will have remains inside and when I demand it, the duct is caught or that, a few days ago I had to change the tension regulator since I started the alternator 22 volt and I burn several things in the car, if someone can tell me where to start checking they are very appreciated ...