problem with Ford Econoline van 1500

Greetings to all in the forum because they will see I have an automatic Ford Econoline Model 98 1500 van, the problem is that it runs well but when I stop in a semaphor or if there is a traffic and I stand for a long time as it wants to turn off if I keep it in Drive but if I return to neutral it remains normal k it will be? I already changed the spark plugs the cables I did full service of an antifreeze tuning oil and all that will be some transmission problem or something like that help me.

The problem is that the revolutions are lowered with load, the solution is to raise the revolutions a bit but in neutral they are very high, do the Relay regulator service, when the vehicles are automatic over time this usually happens to them.

Where this regulator is located and what is done about its maintenance is required to buy something
also what I wanted to comment is that it is not loaded with that fault greetings.

No friend when he talks about loading I mean the weight that the engine does not have that the truck is loaded. This regulator is close to the admission multiple or in it has a two -pin connector, it is removed and cleaned with care with a dic vehicle.