If you are getting white smoke, there is a high potential you have a bad head gasket. The smoke is from coolant leaking into the cylinder and burning off. The "shaking" is most likely a mis-fire, as a result of coolant in the cylinder. And once all the coolant is finally expelled out the exhaust, the car runs fine. It does not resurface until the car has sat and a pressurized cooling system bleeds more coolant into your cylinder(s).
I'm not dead set that is your problem, but it's a consideration. Next, are you loosing coolant?

RPM Guage is known as a tachometer. The tach can bounce for various reasons. If the car was running fine and the guage is acting weird, it could be a failing guage on the cluster or something interfering with the datastream feeding the information to the cluster.

But you have a symptom. From what I'm gathering with your information, it sounds like you have a mis-fire. Now it's a matter of, what's causing it. By chance, do you know the last time the spark plugs and wires were changed?

 

There was one instancewhen I noticed white smoke when the car was idle but I havent seen that in a few wks. I got a oil change yesterday and the ppl recommended treating my fuel system so I went ahead and got that done. Spark plugs and wires have not been changed since I bought the car 8 months ago. I ask the dealer(maroone) and they told me when I purchased the car that everything was changed.

 

Just a random thought, could that possibly be a fuel pressure regulator? Also, if it is in fact misfiring doesn't that pretty much always throw up a code? I haven't seen him mention a dash light on it and I could be completely off base on both of those.

 

I havent got any check engine light so far since I purchase this car.