lalona,
It could be a number of things, anything from the ignition to fuel delivery. IF we new more about your truck and what has been done regarding maintenance, and the miles on it we could narrow our suggestions down a bit to what is the most likely.
I don't know why, but my first thought was fuel delivery, and a clogged fuel filter.
When was your fuel filter last changed?
Your engine does not have a carburetor, but lets discuss what a carburetor does.
It meters air and fuel into the engine.
Your truck has electronic fuel injection. The injectors delivers/injects fuel into the cylinders.
The throttle body, and the Idle AIr Control Valve IAC deliver air.
Combined they essentially take the place of the carburetor.
Your fuel tank has an electic fuel pump in it, that pushes fuel through a filter to the fuel rail,(a set of fuel pipes) and then to the injectors.
Sorry... this is getting too long already.
There is a little valve (looks like a tire valve) on the fuel rail, if you dipress it, fuel should come out. Actually it should be measured with a fuel guage and it should measure 35psi.
When you turn the key on do you hear the fuel pump prime? IF you are not sure, open the gas cap, and listen while someone else turns the key on.
Check the inertia switch (fuel safety cut off switch). The red button should be depressed.
Give it a good visual inspection and Check for vacuum leaks
Checking for vacuum leaks.
Some of the sensors and some of the actuators either read the amount of vacuum, or use vacuum to move controls, therefore it is important to the proper functioning of the engine that your vacuum system is fully intact. Otherwise one may get codes falsely indicating that there is a problem with a controller/actuator, or a sensor when in reality it is caused by a lack of vacuum.
Look at your rubber vacuum hoses (they are about 1/4 - 3/8 inches in diameter, if they are dry rotted or cracked, replace them. IF they slip on/off of their connectors too easily, they may have stretched out a little bit, cut the ends off, and put them back on.
IF you can get it running...
You may listen for a leak. Sometimes using a cut off piece of garden hose is a good aid to listen with. Sometimes a cardboard tube (like from gift wrapping paper) is helpful. Just remember that whenever you stick your head inside a running engine compartment, that you are not wearing any loose clothing or jewelry that can get caught.
Ignition
When was the last tuneup?
Often we'll find that people will have 125,000 miles and never changed the spark plugs.
A tuneup should include air filter, plugs, cap and rotor, The wires should get checked, vacuum lines looked at, and the PCV valve changed.
Are you getting spark?
Pull a plug, and hold it to a ground or clip it to a grounded wire, and have some one else crank the engine, observe to see if it jumps the plug gap.
Of course you could pull DTCs, which would be a great place to start, if a number of parts have already been replaced.
Pull Diagnostic Trouble Codes (DTCs) From your onboard computer.
Your engine and transmission are computer controlled.
The computer uses sensors to tell it a number of different things and it controls actuators that push or pull mechanical levers (kinda). If one or more sensors aren't working properly, the computer goes "blind" and doesn't know what to do. If the computer can "see" but one of the actuators is broken and therefore can't follow the commands of the computer; the engine won't run correctly. The computer is preprogrammed with set values for each of its sensors, and each of its actuators. It will run a self check of all systems, like the space shuttle; it will compare its set value(s) to the value(s) it recieves from its sensors, and actuators. If any sensor or acutator is out of the "normal" range the computer will generate a "code." It will generate some codes on the fly, and others will be stored while you are driving. There is a simple method to "pull codes" out of the computer for one to use for diagnostic purposes.
Earlier versions of On Board Diagnostics OBD 1983-1995 can flash the error code to the dash board and can be pulled in one's driveway without any special tools.
Later versions of On Board Diagnostics OBDII some 1995, and pretty much all 1996 and newer, require one to use a code reader or scanner tool.
Some auto parts stores will scan your engine codes for FREE, you may want to call around. Some will scan OBDII but not the older (prior to 1996) OBD systems.
SO here you go...
How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway
Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more
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