Just replaced my spark plugs on a 2013 C250 Used anti Seize and dielectric degreaser unfortunately. Misfiring and erratic acceleration since. Advise? Replace, clean or?

Did you stick with single electrode Bosch - 0242140512 - or equivalent ?

I stuck it with NGK plugs

I put anti-seize and grease on plugs all the time. Doublecheck your work, figure out what cyl is misfiring, swap the coil, make sure it's a plug issue.

@italian joe1..
what do you mean by swap the coil? Is that ok? Plus I've read that NGK plugs don't recommend using anti seize lubricant and install only dry plugs .. thanks again

If you have a misfire on Cyl #1, swap that coil with another cylinder, see if it follows the coil or stays with the same cylinder.

If everything else is good a little anti-seize on the threads won't affect anything.

it looks like you getting oil into the chamber of the spark plugs that happen to me when I change the spark plugs the 2nd time. So I suggested if you still get this problem change the cover gasket’s as well

Plugs are meant to go in without AS. The manufacturer already has a proper coating on them.

Buy plugs from the dealer.

Anti-seize as noted above affects friction and therefore the torque-tension relationship. MB plugs are indexed by virtue of plug thread tolerance (buy MB dealer plugs), cylinder head thread tolerance, crush washer tolerance, interface friction and torque spec.

To deviate from MB plugs or interface friction (to wit: using lubricant like anti-seize) means that the MB-specified installation torque is not guaranteed to index the plug electrode toward the injector as intended. MB suggests improper plug indexing can cause spark erosion on the valve edge, a cylinder head-off repair process.