highway shudder

I get a "shudder" when I'm doing between 45 and 65 mph. if I turn off the over drive when it's doing it, or drive with the o.d. off all the time, it doesn't do it. I've had the tranny inspected, no problems. The computer read out keeps saying "misfire" on a particular cylinder, so I replace each coil pack & spark plug for that cylinder, but the problem continues and reads a different cylinder. I have now ordered 8 new coil packs and 8 new spark plugs and will install them this weekend. THe question is, what else could it be if this does not fix the problem? Friends I know that say they work on cars suggested computer or torque converter? Any input on this would be GREATLY appreciated. thanks

driveshaft?

Obviously you've got the 4.6L, but what year and how many miles? 2WD or 4WD? How many miles on transmission fluid?

2007, 4 wheel drive, it has 140000 total miles. Tranny fluid was changed when I had the tranny inspected about 5 months ago. I was told to try Mr Tranny Shudder Fix?

Obviously you've got the 4.6L, but what year and how many miles? 2WD or 4WD? How many miles on transmission fluid?

Obviously you've got the 4.6L, but what year and how many miles? 2WD or 4WD? How many miles on transmission fluid?

8 new coil packs fixed the issue for me back when I was having the same problem. It's at a certain RPM that it does it (cruising speed on the highway in top gear usually under light acceleration). Turning off the OD drops it down out of top gear and into a higher RPM making it go away.



I too spent time chasing the misfire and swapping out one pack at a time. Once I got tired of chasing it and put on 8 new packs (Accel from Amazon) the problem went away. I was thinking it was a transmission problem because that's what it felt like from the drivers seat, and even passengers could feel it as well.

Same as A1cntrler, 8 plugs(broke 1) 2 coil packs

Had the same problem with mine. Full tune-up INCLUDING new boots. My Mech said that is the most common mistake the v8 Ford owners make and the cheapest. He did an amazing job, no broke plugs but had 3 coil boots faulty.