Code P0401 - help with EGR, VSV please

Hi,
I have a 1996 RAV4, 4WD.
The Engine Check Light came on, and the code says P0401.

I've seen other threads about the EGR valve, VSV etc... and it all sounds very expensive (with no guarantees you replace the right component anyway).

Does this info. (below) help in diagnosing my problem?

My neighbor has compressed air, so we cleaned the valve, hoses etc, disconnected the battery to reset it, and great... the ECL went off... for a couple of days.

Cleaned out a second time, check light went off for a day, now back on.

Any suggestions?
Many thanks!
Richard

Thanks for those weblinks, but they don't help.
Can anyone answer my question, please?
Thanks,
Richard