Are Boxsters always this unreliable

[Jamesp]

Grumpyfarmer, I'm in the USA, worse still, Texas, so you'll have to pardon my English. When I hear High idle, I'm thinking either vacuum leak, which would come with a check engine light, or an open throttle plate. Since you did not mention a CEL, I'm going with checking the position of the throttle plate. My first guess, since the idle is high but not in a steady state (1400,then 1700, then 1500), is something pushing the gas pedal? Maybe a floor mat? Barring that is the pedal sticking? Have you tried pulling the pedal back to lower the idle? If all of that fails you're in to opening up the engine compartment and fiddling with the throttle body to see if you can move the throttle plate to idle. If this is your primary transportation it's a big deal. But again as a farmer, you can fix any machinery in your sleep.