1997 f150 4.6

It almost sounds like the vehicle is running lean to lack of fuel volume or pressure. check fuel pressure and volume. if you have the proper equipment you can amp the pump to see what the amps are and how the waveform looks. when acting up you can give it a little propane through the air induction to see if your miss goes away, if it goes away you know you have a fuel issue, also check for a dirty mass air flow sensor, this could create the same type of symtoms as well, also check for vacume leaks which can cause a vehicle to run lean, it is alwasys a good idea to make sure your throttle plate is clean along with the idle air control valve, make sure you have good compression in all the cylinders as well, could have carbon build up on the valves but would check the other stuff mentioned first.