oh...this doesn't sound good.
Have you checked your oil and coolant levels lately?
When you get it to idle, what does it sound like?
Is there any mist or smoke coming from the exhaust?
Does the exhaust smell kind of "sweet"?
Have you checked for any puddles under the car?
Any sign of water coming out of the exhaust.
From your descriptions (smelling gas around the engine, water coming out the rear, will barely idle but can't increase RPMs)...sounds like a blown head gasket. Are you sure you seated all of the plugs correctly? Check your coolant level. It it is low, this is another sign. Pull your dipstick and look at it. If the oil looks cloudy or grayish, this is another sign of water in the oil.
First thing I would do is pull all of your installed plugs and put the stockers back in. Examine each plug as you pull it out. You never did say if you gapped them or not.