My car is having a misfire and I want to change the spark plugs

The standing who is not operating well on sharp corners

Trunk stacked in position it wont open and cant be closed, Pulling the lever doesnt make any difference getting this bumping sounds every road barrier or holes. Should I lower the rear seats and open… 

Keeps on shorting when I try to start, I eventually jump start it and the dash flickers for a couple minutes then can sometimes drive or worse case continuous flicks, I’m thinking it might be a faulty… 

Ba light stays on at random times