about 3 days ago my service engine light came on. the car is revving high between 2 and 3 grand, when i put it in gear it drops low and when i first take off it back fires and chokes itself and today it wouldn't start at all and i could smell gas and what smelled like paint thinner. it is shifting really hard and burning a lot of gas as well. i did the paper clip trick and it gave me code 12. any idea's or thoughts are greatly appreciated. thanks !!

 

oh and i just replaced the main pcm computer 3 weeks ago and the alternator and battery or only 3 months old