Dad truck problem

[5.0Flareside]

Ok my dad has a 95 F150 w/5.0. When he has it sitting in park and revs it up to around 3000 rpms then he let off and the truck idled back down and it died on him. He said it happens when the motor is warmed up or cold. It doesnt matter. Any other time if its in drive it runs perfect. He thinks that a idle control is going bad. Not sure. Any ideas on the problem and a fix to it?

 

[john112deere]

Does it have any other symptoms?

Check engine light on?

Sluggish/dirty idle controller could do it, I guess...though it seems a slightly odd way for that to act up. I don't have a better suggestion, though.