Rattling during acceleration

[vando002]

2001 Saturn SC1---1.9L SOHC---Manual Trans----75K miles

This just happened to me the other day coming home from work. During acceleration from a dead stop in first gear, there was this unbelievable shaking and rattling noise from under the hood. I would immediately put down the clutch pedal again, rev it up to higher RPMs and release it into gear and it seemed to be a little better when I did that. I was thinking maybe motor mounts, but I'm not quite sure. I was hoping someone else maybe has had this issue before and could point me in the right direction towards figuring this out. It does it slightly into second gear too, but at higher speeds, its totally fine into 4th and 5th gears. Thanks for any suggestions!!

[RC1488]

Reving the engine in nuetral do you hear the rattling?
If kept at a certian rpm can you sustain a rattle?
With the car off, jiggle the pulleys. do they move back and forth?

Im thinking a bad tensioner or idler pulley.