plugs full of gunk front ones the ones at the rear is ok
a compression test can check head gaskets, or better yet, a leakdown test can check valve stem seals & piston rings. Do you have any other gunked up areas, like the PCV or breather? If oil is migrating into the combustion chamber you may see some improvement with a different oil type/weight (like high mileage oil) or oil additives. Ultimately the only way to know for sure what is leaking (rings, stems) is to pull apart motor, in the meantime try a different oil weight and additives.
what would cause gunk to be in the valves when i took the valve covers off
Most likely most of it is emulsified oil. A dirty or clogged PCV or breather cap (on older cars) can cause emulsified oil to build up. The combustion process can also cause a buildup of carbon in engine. Lack of maintenance over years adds up.
i got motor striped down head gasket is gone