Retrospectively filtering html

Hi, could you tell me if it is possible to retrospectively apply filters to existing nodes?

I have a set of nodes that have styling applied which I would like removing.

ive tried a simple little script the loads each node in turn and then save them again.

However, this dosnt work, i'm pretty sure the filtering is happening aat the client.

Does anyone have any 'out of the box' ideas on how to achieve this?

thanks