I have been having this rough idle for well over a year now and it was more evident upon cold morning startups,and honestly could not troubleshoot the root cause of it even after multiple attempts by the dealer using IDS software and checking for leaking injectors,misfires and adding FI Cleaners,having the intake cleaned nothing seemed to resolve my issues and this all (started after having installed my new PPE CATTED DP)which frankly only purchased two new gaskets because the car was relatively new back then,FINALLY the other day after having my PTU fluid changed the tech noticed that i had a leak on one of the DP which had the (original gasket)and he replaced it with a new one,after a couple of days of driving the car she is certainly rough idle free and anyone looking to have DP installed would make certain to order new gaskets X4 for a secure sealed leak free system,hope this helps anyone out and the parts # are listed below for under 40.00 and a peace of mind. Z http://www.tascaparts.com/auto-parts/2013/ford/taurus/sho-trim/3-5l-v6-gas-engine/exhaust-system-cat/exhaust-components-scat BTW pics below of the gasket that needed to be changed on the DP. Z