Two or three months ago, my f150 had two misfires on cylinder 3 & 6. So I went and got the truck a tune up and replaced two ignition coils, Check Engine light problem solved.

Now the Check Engine light is back on, went to advance auto parts and confirmed my suspicion of having a misfire on cylinder 5.

First is it safe to drive the truck without causing damage to engine.
Is it difficult to replace ignition coils and boots or cables? I have no automobile familiarity or knowledge. Thanks for any reply.