random misfire on 1999 Lexus RX300

dtc 0301 0303 0305 misfire on cyl head # 1 all 3 cyl

Asked by for the 1999 Lexus RX300
Best to check the basics, i.e do a compression test on the effected cylinders, then if the plugs are old, replace them with factory spec plugs. Also check to see if the coils for each cylinder are contaminated with oil from a leaking valve cover gasket. If so replace the coils as well.
These are some of the first steps that I would take to deal with these misfire codes.
Please where are Knock Sensors located? Are they ones at the of top side of Cylinder?