HiCustomer Thank you for asking your question on JustAnswer. The other Experts and I are working on your answer. By the way, it would help us to know:-What year is your Ford?-What model is your Ford?-How many miles are on your Ford?-What type of engine is in your Ford?-What have you already tried?Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.
Can you keep it running if you hold the gas?
The problem you are describing sounds like it could be a fuel pressure concern. I would start with installing a fuel pressure gage on the fuel rail service port and see what actual pressure is when the engine dies, you need to see 32 to 45 PSI. If this checks ok, I would monitor the voltage on the positive side of the coil when the engine dies, your looking to make sure it has 12 volts, if not , then let take a look at the ignition switch as they have known issues with seperation at the switch.
fuel pressure is 40# XXXXX peak and 35# XXXXX voltage at coil is fine
But yet you say it dies right away and you can not keep it running?
yes, it starts fine, sounds great then dies, like something shuts it off, no security system on it either... no blockage in fuel line or filter
Would you describe it like turning the Key Off?
Ok, then from this description I would suspect you are loosing igniton spark, due to the age of the truck, I would start with replacing the Ignition modual and distributor stator.