I have a 93 lincoln mark viii with a DOHC 4.6 and it does teh same exact thing. I put a new fuel filter and new plugs in 2 months for this started doing it so I eliminated them from my thoughts. Then I replaced the fuel pump with a 255 walbro. Replaced the injectors still did it. Replaced IAC (major PITA on my car) and EGR Valve (also major pita), still doing the same thing. If any of you guys figure something out let me know thanks. I think it could be my coil packs so I will try that next.