New to me 2005 SL65 AMG

Mercedes » SL-Class » 2003-2012
Question

misfire on cylinders 3,7, 11....check engine light...resetting light lasted 3 days..light back on....change all 24 plugs or just the ones causing fault??

Remote key fob arms security system..lights flash 3 times, trunk locks, doors DO NOT lock....doors lock when placed in drive, doors lock and unlock when dash buttons selected....key fob appears to be operational: changed batteries, fob light on, infrared beam checked...just won't lock or unlock doors....I haven't checked fuse 58 behind passenger seat fuse box yet...thinking if the fuse were blown the doors wouldn't lock at all....HELP??