98 z28,6 speed....car is down on power and CEL is on...codes are

p0131
p0151
p0418

looks like both pre cat o2's and one of the air pump relays.

what should i check first...just replace o2's or could something else be causing the codes?

should i try replacing the air pump relay or maybe a fuse or could it be something else? what side is "a" the 418 code?

thanks in advance for the help

 

Check the fuses first.