CarGeekIII

I had a similar symptom on my 3.0 liter V6 FWD Fusion at 121k. The symptom appeared without warning. One day everything was fine. The next day the stumble was there. I removed the throttle body and cleaned it thoroughly. After cleaning, the stumble was gone. It has stayed gone after 9 months and 11k miles.

I'm a late comer to this thread, but I wanted to chime in that my 2011 3.0 FWD does the same thing. I have approximately 135k on it, but purchased it at 50k. At 70 MPH I can feel it pulse in and out as I travel down the interstate. I can accelerate it up to 90 MPH and it does not miss a note. In cruise, it pulses. Most of the items mentioned in earlier posts I have considered as potential fixes. The only item that I have done is that I have cleaned my throttle body, for other reasons. It had no effect on the pulsing, but did fix the off-idle acceleration problem. The only other thing that I thought might be variables: Is the transmission torque converter is going from lock-mode to unlock-mode? Many modern cars have a torque converter lockup mode in order to achieve better fuel economy. I am not certain that this transmission is so equipped, but I would guess that it is. Is the fuel pump changing pressure levels? Is there a brief vapor lock in the fuel rails on the engine under the high temperatures of a continuous highway drag of 20 minutes or more. By the way, I had a similar issue in my old 2006 Taurus. I bought that car at 55k and ran it up to 130k. It had a completely different 3.0 liter cast iron push rod V6 and different transmission. I would really like to get this fixed. I like my Fusion a lot, but things like this are definitely detractors to the fun of driving it.

I have experienced this with my 2011 3.0 liter. It began around 110k and continues at 135k. I've attributed it to a lifter problem. As stated, it does not seem to affect the running of the engine. For lube, I've been running Castrol Syntec 5w20 in the engine for quite some time. I was considering some Marvel Mystery Oil about 500 miles before my next oil change to see if that will clear it. On a related note, my Nissan Titan 5.6 liter V8 does the same thing. It began at approximately 80k miles and persists still at 98k.