Gasoline vapor lock

The issue sounds like vapor lock, The temperature in the engine compartment is so high that the gasoline is turning to vapor in the gas line. There are not many options available in your situation except to travel at night when the temperature is lower. The problem is compounded by gasoline that has ethanol in it. A fuel pump that has low pressure can contribute to it and some people are able to control the return line pressure to help this.

If it is a gas engine, its almost impossible to get vapor lock.
Vapor lock is when liquid gasoline turns to a vapor which will not flow thru a carburetor. The usual cause was hot fuel lines going to the carb.
Since the early 1980s engines have used fuel injection which uses liquid fuel under pressure.

Check the fuel pump pressure. IF this is heat related, it could also be a bad gasket causing a vacuum leak. The other thing could be the fuel line is getting too hot causing the gasoline to create a vapor lock.

Not really possible. True vapor lock only happens on vehicles with carburetors. The gasoline would vaporize from excessive heat before reaching the carb.
What are your symptoms ?

Vapor lock is when an engine with a carburetor gets so hot the liquid gasoline in the fuel line vaporizes.
Cars with fuel injection use pressurized fuel lines and are almost impossible to vapor lock.

No.
To begin with, there is no such thing as vapor lock in the cooling system. Vapor lock is when liquid gasoline vaporizes due to excessive heat. If the engine got hot enough to turn coolant into vapor the engine would seize up.
Do you have trouble code numbers ?

To promote easy starting, all gasolines contain volatile constituents that under some conditions, such as high ambient temperature, tend to produce more vapor than the fuel-system vents can handle. The action of an engine-mounted fuel pump, in decreasing the pressure at its inlet, tends to vaporize the fuel. If the vapor forms faster than the pump can draw it from the fuel line, the flow of fuel to a carburetor is effectively stopped and the engine stalls. Vapor lock is much less likely on a fuel-injected engine with an electric pump in the fuel tank. However, an engine with port fuel injection may experience vapor lock if the injector or fuel overheats, or if the Reid vapor pressure of the fuel is too high.

Read more: http://www.answers.com/topic/vapor-lock-1#ixzz2Pf13O7aL

I understand what you are describing, but keep in mind it is almost impossible to have an actual vapor lock on a fuel injected vehicle.
Vapor lock is when the gasoline in the fuel line turns to vapor before it gets to the engine.
I am assuming your Ford is newer than 1982 and has fuel injectors.
In your case it could be a vac leak or something making the fuel mixture too lean. A problem with the EGR valve or other component could cause the issue.
Is the check engine light on ?

water pump or a vapor lock in ur water system

make sure theres no air in the system causing vapor lock.

If it's not that i would start looking into head gasket issues.