playguitar

Hi, My 85 F150 4x4, 4 speed, 5.0 Fuel injected is sick.
The gas pedal was stuck, so I checked the throttle cable which has a plastic tube within a spring at the end where it connects to the throttle body. The plastic tube has deteriorated and needs to be replaced. I disconnected the cable and then noticed that the butterfly that is inside the throttle body is jammed shut. It will not move at all.
Can somebody help me . I need to know why this is so and if I should remove the whole thing or what ? Also do I have to get a new throttle cable or can I just replace the plastic tube that is within the spring?
Thanks for all replies.