Why does my 83 ford LTD die when I go down hill?

hi david.
not sure if this link will help you out but have a look.
1983 ford ranger 2 3 engine starts but will not idle Google Search

When was the last tune up? There is a few things that come to mind. possible low fuel pressure, dirty fuel injector, throttle body could need cleaning, dirty fuel filter, water in the fuel, spark plugs need to be replaced or re gapped. I need more information to try to be more helpful.

what engine do you have?

it is usually under the dash on driver side, maybe behind kick panel. Sometimes on passenger side but not ofiten.

you need a new idle air sensor

check and see if is getting any spark out of the #1spark plug wire .if not change out your distributor cap ,rotor button and spark plugs wires ,and plugs

It could be dirt in the idle jet or a problem with the idle solenoid. what should solve the problem and generally improve the performance and economy of the vehicle is a tune up and possibly a service. This will iron out all those niggly problems.

The 83 still used a carb and mechanical fuel pump I believe.
And the fuel pump is probably bad.
Check the oil and make sure it is not over filled with gasoline.
Take the fuel line off the carb, and see if the pump squirts when engine cranked.
Open the gas cap as well, so make sure a stuck purge valve is not holding the gas back.
http://www.autopartswarehouse.com/details/QQFordQQLTDQQAirtexQQFuel_PumpQQ19831986QQAF60048.html

check the coil and for spark

I likely have the pic you need. But first, what are you working on? You have a 84? 83? Crown? Did you put this motor in? What is it out of?