Thanks for the question.
I would check to see if the cat-converter under the vehicle is getting really hot or not. If it is, too much fuel is getting into the exhaust system, or it is partially plugged.
Thanks
Fordanswerman
FORD MOTOR COMPANY CAR AND POWERSTROKE SPECIALIST FOR OVER 16 YEARS. ASE MASTER SINCE 1991. CURRENTLY WORK AT A MAJOR FORD DEALERSHIP. GIVE ME YOUR FORD PRODUCT QUESTIONS, IF I HELPED, PLEASE HIT THE ACCEPT BUTTON. EXPERTS QUESTIONS ON FORDS WELCOMED