Jumping in here, How do you know if your vacuum pump is going bad? I have an '05 superduty that has a vacuum gremlin. Mine works like a charm, most of the time but if it is hot, just the time when you don't want this to happen, it seems to quit. I popped the hood to check the pump, and popped the line off and the pump ran for a second then stopped. Plugged it back in, nothing. Unplugged the wire to check if there was a cut, wire was fine. Plugged it in and it ran and wouldn't stop until I shut the truck down. Started it back up, pump not running but the ac was working fine.
Anybody that can point me in the right direction I would greatly appreciate it. I have the ford dealer service manual coming, hopefully that helps.