[BALLSS]

the harmonic balancer should not wobble and certainly can result in your car "shuddering".

The rubber on the balancer may be old/cracked causing this. A replacement balancer is needed. you can unbolt the balancer from the hub to replace

 

[BALLSS]

it is much more common for the rubber to break down in the balancer itself and start to wobble than the hub being bent

as noted pull belt and see if damper spinnning wobbles. If so remove just the outer balancer and start engine again and see if hub has a wobble in it.

the wobble is a sign of part failure which may or may not be related to your shutter but certainly a suspect so fix it and move on from there if you still experience shudder...which could be many things with ignition issues being one I would look at next.. If thse check out pull dust/inspection cover from torque converter and inspect flexplate for cracks. you will have to rotate the motor to see all of the flexplate under those conditions and it still may be hard to see if in fact it is cracked.