2002 T-bird

I have a 2002 T-Bird that has a bad vibration and miss. I have had it in the shop numerous times. The fist 2 times w/i 2 weeks of each other I had to have coil pac replaced. It ran OK for a few days both times then started to miss again. Next time they replaced the fuel cell(ford paid) which was supposed to have been the cause of the coil pac problem. Well w/i a week of that it is missing again and has a vibration I can feel in my foot when I press the gas. The engine light has come on and it smells of emmision. HELP.. Please