06 Rwd is250 166k miles

got these codes today from my scan tool

i understand it’s a misfire for cylinder 4 and 5

i am not the original owner and had it since about 160k miles

aside form the spark plugs and coils is there anything else I should look for

i had also recently put regular in it say the last 10 fill ups and has been running fine so not sure if that is the cause or contributor

its not my daily driver and I may drive it several times a month

i do notice an engine shake recently at start up

Also the p0304 code also had a “p” at the end so not sure that means “p0304 p”

thanks