Not that I would ever defend Ford, but the OP's issue sounds like a dealer problem. Or, more specifically, a "system" problem.
The dealers and the mechanics are paid little or nothing from Foird to troubleshoot. They make their money from fixing items that are cut and dry -- particularly when they can do said fix so many times, that they finish it much faster than the hours for which Ford is actually paying.
This is why they send the cars home with excuses when the problem is not obvious. It's also the reason we get the "normal operating characteristic" so often from dealers. Sometimes that's Ford not wanting to pay for a fix (like with the ticks), but it's often that the dealer doesn't want the headache without the payout.