Do these EQ's have only 2 O2 sensors? I'm looking to replace them this weekend, should be fun. I'm planning on using the exact fit Denso's. Are these pretty good? We receive the P0420 last week. I know it doesn't point directly to the O2's but we are noticing poor MPG's and we have about 88k mi. so I guess it wouldn't hurt to replace both. I'd appreciate the help/advice.