Saying a starter is "sticking" means that it it staying engaged longer than it should/not disengaging when it should. This could mean that the solenoid on the starter is failing and not disengaging the flywheel properly. That noise you hear is the starter grinding on the flywheel.
The other reason for the starter "sticking" is that its being told to stay engaged. Like when the ignition key is turned forward. Since your grinding noise coincides with a loss of power it would seem your ignition is sticking in the "start" position, causing a loss of power and the starter to stay engaged.

Try jiggling the key.

 

If I'm reading this right, North Shore is saying that the car is running fine for a span of time and then the noise is heard.

I understand that the starter can be stuck, but is it really likely that the starter was spontaneously re-engaged after a while of not being engaged? Randomly?

I'm not saying anyone is wrong, just that it seems a little strange for the ignition and starter to get spontaneous and random.

 

My theory is that the ignition switch is right on the verge of the "start" and "run" positions and then hitting a bump or stopping or who knows makes the key turn to the "start" position and then all electrics stop (just like they are supposed to) and the starter engages and grinds the flywheel.
Thats why he needs to JIGGLE THE KEY the next time it happens.

 

Walt is right. It is random and spontaneous. The noise dosen't start untill I switch from drive to park. I notice the electrical isn't working ; I go to put it in park and the noise occurs. The noise wont go away until you turn it off, tried putting it back in drive, tried all gears. Just turn it off, it goes away, they when I restart the truck, it's gone, electrical works, like nothing happened. Could be quite some time of driving before this occurs, only randomly when I go to put it in Park.

Thanks for the replies so far.

 

Am I invisible?
Have you tried jiggling the key when it happens?

 

I was going to say on the last message, but we will try jiggling the key whenever it happens again, it hasn't happened again yet.
Thanks.