First of all, any situation where you are smelling the strong odor of raw gas (fuel) is very dangerous. Fire or explosion are very real dangers. The very first thing you need to do is locate the source of the "gas smell" and eliminate any raw fuel leaks or explosive mixtures that are not inside the engine where they belong.
Also, I will need a little more information to try and help you. You say 6 cyl. Engine but is it the 3.8 (3800) or 3.4 (3400) V-6. Also, when you say it revs to around 4000 rpm when you put it in park, is that constant or for a short time before leveling out to a normal idle? I suspect it is constant and is the cause of your bucking and "someone pressing on the gas" description.
Right now I can only guess that maybe your throttle position sensor or fuel rail/injector system has a major problem. Is the check engine or stop engine light illuminated on the dash? If one (or both) are on, the best course of action (even though it is a bit expensive) is to have a diagnostic test run to find out where the problem is. Sometimes major, national chain type, auto parts stores have hand-held diagnostics they loan for you to determine your problem. These are a second-best option to a full repair shop diagnostic test but if $ is tight it's an option. Good luck and I hope you can answer my questions so I can try to help you further.
Tuesday, October 19th, 2010 AT 12:29 PM