This has been on here before but got no replys on it will try again. Have a 2004
screw 4x4 5.4 lariat. It seems like the ac is kicking in and out but I have turned
the heating and air off, and it still does it only at hiway speeds. Can feel it going
up hill like your running into a light wind gust Dealer said everything check out
ok on road test. I know its there because I can feel it. I can't be the only one
this is happening to. No it not the fuel filter. Not bad gas.

 

Bro, I have the same exact truck, no probs here. The A/C light will illumintae but it kicks the temp that it reads.

I'd take it up with Ford to see if you can get another opinion, or different mechanic to check it out. Sounds like the dealership isn't taking care of it's customers.

Good Luck on you cure!!