low idle after auto warmup

Take a look at your throttle position switch.

 

Easiest first diagnostic step would be to touch/"feel" the frequency valve (aka metering valve) during the bad running so you'll need an assistant (also "feel" it during the good running to calibrate yourself for how it should feel during engine running) -- it should always be vibrating/buzzing whenever the engine is running, so, if it isn't during the bad running that would indicate that the operation of the protection relay should be checked.

If the bad running is very smooth, but weak, another relatively easy thing to do would be to confirm/deny spark on both banks.

Good Hunting!

 

My experience tells me that if it has tits or tires, it'll eventually cause problems.

 

Might check the water temp sensor part number 125769 under the intake plenum. You can get at it with the oil filter off with a deep socket and extension and a bit of hand work to remove the wire connector. It provides input to the fuel injection system ecu. It is a simple resistance thermistor, but can get deposits on it that make its readings inaccurate.

 

That sensor is only present on your KE3-Jet with Lambda 328 (it's not present on a US version K-Jet with Lambda 328).