Dropped oil pan - findings / question

[AAzz44]

Taking advantage of this winter and doing some maintenance on my A. I dropped the oil pan and wanted to run a few things past the group.
I noticed what looked like carbon build up near the front. Is this possible? I added photos to share.
Also pulled the spark plugs (which I replaced about 3 months ago) and here is how they look. Lots of carbon build up.

I just purchased this car about 6 months ago and noticed it always seem to be rough idling and lacked power. Been trying ti find out why since than.

Thoughts on why you see and where I should go next?
As info, oil pan was actually cleaner than expected with very little sludge build up.

Thanks
Mike