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Q IN Q issue, input errors, dropped packets due to MTU ?

Hi all

I seem to be having an issue with my dot1q tunnel, since migrating to a new switch

We have moved from a 3750x with the jumbo mtu set at 9000, and when I do a show interface I see the interface mtu as 9000

now we are running a 6509 with the tunnel interface now set on there

however the port MTU is 1500

on this port I can see lots of input errors, and also have seen storm control drops, the storm control was set at 10 for mutlicast and broadcast, we are also seeing very low response times for things going through the tunnel.

My question is, is this most likely an issue with the MTU size?

and if I was to change the MTU size on the interface would it cause the link to go up and down ?