Misfires are usually caused by a lean condition. It would be nice to know if it's happening on the same cylinder or randomly on all of them; of course, without a scope or misfire monitoring that's not going to be easy.

Once you've got it in a 'glass smooth' condition, I'd take the caveman approach and start tapping on things to try to induce a misfire. You could also take an upside-down can of air duster and spray it on things like the ignition control to cool them quickly.

Without the proper tools, it's sort of hit-or-miss.

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.