Gday all!

I have a 1987 244 with LH 2.2 that is cutting out when hot. after it stalls it will restart and run like nothing is wrong for the next few mins and then will stop again. If left overnight you then have a good 20mins of normal driving until it all starts again.

I got it home, left it idling and noticed that after a few mins the idle dipped for a moment then went back to normal. After this dip in the idle, if you touch the throttle at all then it will stall. before the dip it wil run normally.

Checked base idle and mixture. O2 sensor is fluctuating normally at idle. If the throttle is held at 1500rpm then the O2 sensor doesn't fluctuate but indicates a rich mixture that slowly richens to the point that the engine can still run with the brake boost vacuum line disconected.

Engine is drivable with AMM disconnected in limp mode.

I'm about 95% sure that the AMM has failed but I'm looking for any suggestions regarding something I've missed or another way to confirm AMM failure (I don't have a spare here).

Thanks
Alex.
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Alex Shevlin (Sydney): '69 122S, '87 Merc 190D