Hello from Atlanta. Getting ready to change Avalon rear valve cover gasket. Car has 150k mi. Read various info that talks about changing, among other things, spark plug tube seals and seal packing on semi-circular plug grooves at cam ends. Should I buy these items in case they're needed, or are they probably mandatory at this mileage? Already have air plennum gasket and vc gasket.
Also, what's the recommendation on reusing/replacing egr and throttle body gakets?
Thanks in advance.