Went and had a look at the o2 sensor and wiring. The wire went almost against the exhaust manifold and a corner of the plug was melted a bit. So I undid the plug and re-routed the wire behind another pipe so it can't touch the manifold, reset the computer and its all good.
Thanks for you help guys.
p.s. that page from supras.com is very helpful. I will have to add that to my favourites
Thanks again
Binny