OK, returned from holiday - maintaining the Boxster.
Removed and cleaned the ICV, was not too badly contaminated, noticed a crack in the plastic body of the valve, but this did not leak air.
Sealed this with hot glue and self-amalgamating tape.
Checked operation of the valve using alternative power source, open and closes fine. Refit with new gasket, started up and ran fine (cold).
Hot start still a problem (Daytime temp mid to high 30's Celcius, started fine when ambient temp less than 30c.
So still suspect fuel vapourisation, so have removed and checked fuel evap canister, did find crack at base where one of the vent pipes fits, repaired and refitted.
Fuel system still honks but only once everything warmed up.
Checked connections at top of fuel tank, can't help but think there is something not sealing correctly in the fuel system, so that fuel evaporates when stopped and temp is high.
Engine starts by depressing throttle and holding just open once fired up, settles down after approx 10secs and idles ok.
The idle is much steadier after cleaning up the throttle body.
Anyone got any more suggestions (can't see it being the Crank Position Sensor as this would not suddenly work by pressing the throttle).
