Pick up a set of o2 sensors and plan on replacing them today. Truck has 175k on it and they are the original so fig can't hurt. I looked at them this morning and their positioning sucks. So I am a little slow to start.

 

If you remove the plastic inner fender it makes it a lot easier. It's just a few philps head screws and some plastic panel retainers. I would also check out the tool section at autozone, they make a O2 socket.

 

You can try and easy fix for the pinging.
Get a spray can of contact cleaner and spray out your MAF.
I have cured several that way. The sensor gets a build up on it and can't measuer the air flow right.