Dang.. missed the cutoff time to edit my previous parts compatibility post...

So, I pulled the IAC, pulled the known good one from the donor car. Same part number. Cleaned it, installed it.

By now, car was cold, and it started right up, no gas pedal application. Car immediately went to about 1200rpm, then settled into a nice ~800rpm idle which seems normal to me.

I just left it running and it loped along normal for about 3 minutes.. about the time the temp gauge barely started to rise, it started slowly and minorly surging.. maybe from 750 to 800rpm.. every couple seconds. As it warmed up more, the surging got less minor, more like from 600-800rpm, and more frequent..

Then, eventually it dies. It will restart after dying with a little help from the gas pedal, but it won't idle.. not until I let it cool down.

This is exactly the same behavior as before I swapped IAC units...

When driving, it's always got tons of power, so I rather doubt it's fuel starved, but that it always starts up.. leads me to believe it's a fuel issue of some manner, not ignition...

it will continue to idle with the slightest touch on the gas pedal.. tempting to turn the little screw under the throttle switch, but I don't reckon that's proper...

Any thoughts? Unfortunately, I have no Bentley, and I've got about every early-mid '80s 240 green book except the one that covers turbo K-jet troubleshooting. frustrating that...

Thanks as always.
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-Matt I ♥ my ♂