I can hear the rattle under the hood so im assuming its something in the engin but i am not sure i cant locate it. and it only seems to do it if i am stoped or at a slow idle, any suggestions... could it maybe be a lose nut or bolt that fell into the engin?

If it was a bolt falling into the engine, there'd be more than a "rattle".

Could be anything from an engine not running on all cylinders to a broken motor mount. Do your homework - sooner or later you'll find it.

where is it coming from, like location on engine? top, bottom; front, back ?

when i rebuilt my carb, i accidentally dropped the TPS rod into the engine. when i started it up it was a slight ping, as if someone were tapping a screwdriver on a fan blade.
i dont know why this matters, but its true.

engine rattles are tough, good luck