I've experienced no idle issues till today. Car has a newer upper wire harness, fresh plugs/wires. New vacuum lines. I'm thinking it's a failing ETA but I'm hoping it's something simpler.

Symptoms:
Start up: Jumps immediately to 1600 rpm, drops to 500, engine shutters. Is does this 3-4 times then moves on to the "cold engine idle" symptoms.

Cold Engine Idle: Fluctuates from 1000 to 500 rpm, @ 500 shutters. Repeats this pattern till engine warms up (88c).

Warm Engine Idle (88c): Fluctuates between 600 to 750 rpm. If I place the car in D,3,2 or R the idle is normal (600).

If I start the car when the engine is warm the idle surges to 1600 drops to 500, shutters then fluctuates between 600 to 750 rpm.

While driving the car everything seems nominal. No hesitation in the acceleration sits solidly at 2500 rpm @ 60 mph.

I checked the cruse control and all functions work.