It only surges after reaching operating temperature, 80c. I've checked the throttle micro-switch for continuity on/off and lubed it as well. I don't believe the CIS-E injection system ever shuts off fuel, it's constant unlike the LH hot wire system which does cut fuel. I'm thinking it may have something to do with the EHA valve as I turned it up just a tiny bit last year to improve drivability but this surge issue is new.

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1988 300E