engine shaking at start up..

[solrac6262]

Hello all
I have an 07 3.0 with 45k on the clock...
When I start the car, the engine shakes for a couple of seconds, my rpm needle moves up and down a little, then return to normal as soon as the shaking goes away...some times x5 its fine, I've been doing a little bit of research, another member posted that his problem was fixed changing the MAF and the transmission mounts, can someone comment on this, if you had the same problem and dealer fixed.. other mentioned that it can be the fuel pump or changing the fuel filter..

also have the CPO but not sure if this can be covered under warranty
thanks all