Engine 99 Rough Idle, Sputtering

I see you haven't gotten any responses on your issues, I have the same problem with my 01 V6 with 96000 miles, i have JBA Headers, BBK Cold Air Intake, ASP Underdrive Pulley, Richmond 410 gears, Flowmaster Dual Exaust Diablo Performance Chip, and Venom Computerized Nitros 100 HP Shot except sometimes it will go for several days and not miss at all, then start back agin, it never has an engine code, Ive taken it to ford dealer ships and theyve driven around with a laptop in their lap and still can't figure it out, taken it to mechanics that only work on mustangs no one can seem to Figure it out, I've replaced the head gaskets twice, the plug wires and plugs three times replaced the coil pack, had the upper and lower instate gaskets replace, replaced the resister on the coil pack, ford dealer ship replaced every sensor they knew and checked for vacuum leaks, when they couldnt figure it out they blamed on all the modifications id done to the car, the modification were removed except for the 410 gears and put back stock, still its been 6 years yes years no one still hasn't figured it out, so I put everything back like I had it, and just drive, it's an awesome running car even with the miss its pushing 300 hp and 300 ft lb torque like it is, would love to see it full potential, hope you have better luck figuring yours out than I did.....

Mike Connell said:

I found and fixed the problem. There was a crack between the valves in the compression bowl if the head. Was causing the gas to exit the piston prior to spark plug firing and was the cause of the exhaust sucking in

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Glad you found and fixed your problem....