okay so a few days after i got my car from my aunt the servie engine soon or check engine soon light came on..I cant remember which but whenever i turned my car on it shook pretty bad and then it went away and then it acted up again. I replaced the air filter a week ago and on friday when i started it up to leave school it started shaking again and I said some 4 letter words i cant repeat on here. and so anyways ive tried the whole diconnect your battery thing so its not that and it almost sounds like its firing wrong. my grandpa thinks its a coil going out. anyone have input?