Incorrect Timing Adjustment causing heat issues?

I think it might be. I brought it to them set around 10 degrees base timing. (Pretty standard.) they apparently adjusted it because it was “misfiring” at around 2500 rpm...? Which I would understand if it was knocking you would retard the timing but a miss fire is a separate ignition issue that also needs to be addressed. Bad ground etc.
It also feels like l what little power existed is gone. It seemed to get hot enough on the very last bit of my drive to give either a big back fire or a singular bad knock. It also seems to skip a beet every few rotations at idle which would be more down the timing misfire road.
Is it possible that I need a new cap, rotor and condenser if the accidental left the key in the run position while off?
IMO it sounds like you need to find a new shop that is competent that you can trust. Or better yet dig in and start doing your own tuning, it's not difficult if you follow the basic's.