My buddy has had the stumbling problem with his 2012 ecoboost on several occasions. The TSB has been performed and the shield installed. It has seemed to help, however, we have discovered something when he drives in the rain. It will bog down and stumble after driving in the rain. I advised him to look in his airbox. We pulled out the filter and the bottom of the box was full of water.

We both went out and drove again in the rain on another day (mine is a 2011, his 2012) and checked out airboxes. Mine was dry, his had water in it again. If his airbox keeps pulling in water, that is a major problem!

 

I believed this to be a major problem also. The gotts mod that it comes with allows rain into the box due to the grill. Try this on the 12 ta 13's http://5startuning.com/onlinestore/e...ntake-kit.html Your grill may be different in the frontal area. Believe it is still a problem on most of em. I would cover the inside of the verticle fins on the grill at its side to slow down the water also on the side nest to/ in front of the headlights. Tis my belief injestion of liquid H2O is a major contributor to condensation in the "CAC". Of course Engineers know it all nowdays so let em take it in the ars on this one if possible.

 

That's interesting... Mine actually fell down on me for the first time this past weekend.

Was pulling hard getting up to speed on an interstate onramp. She fell over for about 2 seconds at about 3500 rpm, then pulled again. I had just run 55mph through a massive downpour.

Have driven a couple hundred miles since and she has not fallen over again but I bet there was some water in the air box.

I will pull it apart tonight and see if I can see water remnants.

 

It is not unusual to see a water rust line in the air box, but I would worry about one of over an 1/2 inch deep. All I have ever seen was some moisture in the bottom corner. But it does have a water line in it abut 1/2" from the bottom so following a semi must spray some into it. Maybe driving style, following close in a storm would pick up a lot more. I always drop back from em and switch lanes on the expressways to the inner most to get from the crowd.

 

I just got back from a 2200 mile trip and coming home yesterday we drove in rain for 3 or 400 miles. After a while of driving in the rain I got on it to pass a vehicle and the thing just fell flat and started stumbling. Backed out of the throttle a bit and it would accelerate ok. One hill outside of Omaha on I-80 I tried to pass a truck and the thing stumbled and sputtered and then threw the check engine light. The AC shutdown and the truck vibrated and shook for a few miles and then it cleared up, light went out, AC came on and away it went. No problem once no more rain.

I have not looked in the air box to see if there was a water line. Being here in CO we haven't had much worry about rain this year so this was the first time driving it in an extended rainstorm. Hope they get it figured out so I don't have a repeat when towing my camper.