You can maybe get the DPFE sensor from someplace like Napa or Autozone.

Personally, I'd try all other options before I would consider the intake/hotwater bypass trick.

I'm sure you've read through this Forum's threads regarding some of the other things you can do to improve the performance of your engine....clean the MAF, clean the Throttle Body, new plugs/wires, etc.... All these things can help in your battle against pinging.

You might also want to try doing a search on "ping" or "pinging" in the Ranger Forum where Ken00 presides. The issue has come up quite a few times over there.