Got the Shakes

[NeishaXR8_347]

My car has developed a lil annoying problem, its kind of a little shake/vibration but it can't be pin pointed because it doesnt not do it all the time.
Things it does: 0-50km/h sometimes it shakes and most times it doesnt.
50-100km/h sometimes it shakes and most times it doesnt.
Because sometimes it does and then doesnt i can pick it. I first thought it was the tarp flapping in the wind but it does it without it.

My thoughts are:
-A wheel weight has come off or they are just poorly balanced.
-Front shocks are getting on and causing this feel. Rears are Brand new.
-worn front end rubbers/bushes
-Cant be brakes because they are all new and it was there before them.

When it shakes it shakes my front door a bit and you can hear the rubber door seals rubbing together.

Any thoughts? or anyone had this problem?

Shaun