IS there a way of testing these before I fork over the cash to buy new ones? Specifically the MAF power and burnoff relays...

You can do this if you have a service manual (GM, not Haynes, etc.). Simply look up the relay wiring diagram in the back to see which wires see voltage when the relays are engaged. Then apply voltage to that wire, and test the 'output' wire of the relay for power. I seemed to have misplaced my manual or I would look it up and scan the pages for you.

Hope this helps.

--Dave