Because of its internal design (built-in series resistor), resistance measurements of the AFM pot are not that revealing - in-use voltage measurements are needed for evaluation. Still, your other tests seem to indicate you shouldn't concentrate too much effort on it. Rotating it experimentally should be proceeded by very carefully scribing an index mark, so you can accurately return to 'go'.

Maybe time to scope the engine - e.g. you may have lost ignition advance or valve timing off.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7