Chevrolet Repair: 95 Blazer Problems, intake manifold gasket, chevy blazer

Question
Van,

Currently i bought a used 95 Chevy Blazer. I was wondering if you can tell me why the car shakes a little when I am stopped at a light or parked with the engine still on.  The RPM indicator moves up in down a little when I am idle or stopped as well.  The car sounds very odd, and the exhaust seems to have this sputtering noise instead of a smooth hum.  Lastly, There seems to be some strange odor coming from somewhere from the car.  It smells like exhaust a little bit and seems to be making it's way in and around the car.  Please help me out.  

-Austin

Answer
Hello Austin,
One thing I can think of is a vacuum leak.
Another would be dirty injectors, causing the catalytic converter to overheat.
Sputtering out the exhaust could be from an exhaust valve not sealing, or the timing retarded.
If coolant is dissappearing with no leaks, a leaking head gasket or intake manifold gasket could be the cause, and that would smell kinda sweet.

Van