My dealer recommends "decarbonizing" the throttle body (by soaking it in
solvent) of my Odyssey every 2 years for $179. He says it's due to the
cheap gas and, god forbid, the carbon migrate all the way to the catalytic
converter.

I'm a little confused since I picture the throttle body as being before the
cylinders/combustion, and the catalytic converter as after...

But, none the less, has anyone heard of this and is it worth it?

Thanks