On my 87 300e, built in October 1986, I'm trying to eliminate off the line sluggishness first by leaning the mixture. So, using my Sears digital multimeter, with key on engine off, the reading at pins 2 and 3 on the diagnostic socket near the left fender is 90.5% (there is no pulse counter socket near the battery). According to the manual, with the engine on and warm this would mean a bad EHA if the engine was warm, but would that apply before the car is even started? When the car is on, the duty cycle stays unchanged at 90.5, and I was going to swap the EHA for a known good one to see if anything changed. I'm also planning on calculating duty cycle using the voltage test to see what that produces. Is the % duty cycle supposed to work on a car that old? Any thoughts? Thanks.

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87 300e (white/black; amg body kit)
88 300ce (red/cream; amg body kit)
93 300ce cabrio (white/blue/blue top)
93 300ce cabrio (black/grey/black top)
98 ml 320 (totaled @ 137,000 miles)
99 clk320 (black/grey/black top)