I cleaned it until long after it was shiny. It seemed to move freely and the spring return worked although it didn't feel overly strong. I got between 8.2 and 8.4 ohms across the connectors with a cheap multimeter.

After reinstalling, the problem remains. If I tap the IAC while its surging, the idle drops to ~1100 rpm and is fairly steady for a short while and then it begins fluctuating again at the lower rpm level. It varies maybe 200-300 rpm. If I tap it again, the revs drop again and so on and so forth until they drop so low that it will stall.
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92 745T 125K; 83 242Ti 188K - Brick on blocks for now.