Misfire
 

Just picked up a 95 3vze with 215000
had been siting for a couple years, when we went to start it we hooked the battery up reverse polarity. Once replacing the fuses that popped, it drives but misfires on cylinder 3 and has a engine code 25(lean air)
Replaced the spark plug n wire, didnt fix it.
Im new to this engine, so any advise helps.
Havent done a compression test yet, i was gonna try the injector next, but was wondering if the reverse polarity battery might have blown any electrical things i should check


Ive heard about valve tunes, they sound a little complex for my skill level, when should i think about getting that done? When i can hear them slapping?

If i run a compression test and find low compression, its likely a valve, in which case i would have to open the valve covers and adjust it anyway, right? How hard would it be to just do the rest of them?