89 f-150 help
 

My 1989 f-150 f series is making a noise and i cant solve it

the trucks has a 5.0 in it, sitting at idle there is a ticking noise, but as soon as you give it gas, the sound goes away. Sitting in the truck it is a very prominent sound, the motor has been taken care of, truck only has 146,000 on it, oil change every 3,000 air filter every 5, Any ideas?