My 2004 mercury sable started stuttering when i would push the gas(like it was struggling to get gas)and when I would come to a stop, it would idle really high and stutter. Two days after this started my emissions light came on. I have changed the gas cap, cleaned the throttle body completely and replaced the throttle position sensor. The car is still running the same way. WHAT ELSE COULD IT BE? Sometimes the emission light will start blinking and the a/c will go out while it is blinking. Help!!! I cant afford a huge mechanic bill right now.