How to replace 2000 Ody plugs

I do my own basic maintenance - oil, filters, fluids, plugs - but am stumped by my 2000/77k miles Ody that seems to need a spark plug replacement. Looks like there is just a space for an allen key to open up an electrical connector to (perhaps) get at the spark plugs.

The spark plug connector etc are like nothing I have seen before, and I was not able to find a Chiltons for help.

Is there a site that helps?

Has anyone tried it before?

Any advice would be appreciated, since I feel the time has come. At 1500 rpm or so, the engine hiccups and needs a bit of gas, else it threatens to stall.

Thanks!