Without being able to see the thing, I really think that it is vacuum or intake air leak issue. Just my 2 cents...

 

Thanks for the assistance everybody..... I think i got it. The Vac line that comes off the back of the intake manifold was not connected securly. I started just giving everything a slight tug and it fell right off. Took it for a spin and there is no vibration/rattling on acceleration and holds a steady 600-700 RPM at idle. Thanks again

 

glad it worked out.