The car is a 2002 Nissan Almera 1.8L ATX.
Normally the car idles in park about around 700 - 800 rpms and was showing a long term fuel trim of about -10%. Then one day I was sitting in park and all of sudden the rpms jumped to about 2500. I shut off the engine, and after restarting it, it was still idling high at about 1000 - 1100 rpms.
This has happened twice more since then, and the idle in park won't go below about 1000 rpm. The fuel trim is now about +7%. There are no trouble codes.
I took the car into a shop and they hooked it up to a four gas analyzer and it's lambda is perfect at 1.000, both at idle and held at 2500 rpm.
Maybe this could be a malfunctioning IAC or some other idle up device? How could I tell?
One other thing which seemed odd was that Calculated Engine Load seemed pretty high. It was 33% when idling in park.