Check for vacuum leaks, give the AFM a thourough cleaning with Carb Cleaner, and check your plugs, wires, cap and rotor. I would even venture to guess that some healthy doses of fuel injector cleaner would also help. See it seems your idle is just not raising high enough to smooth out the engine when AC is engaged. Could be a weaker spark, clogging up injectors or just plain dirty AFM and intake. So check some things and hopefully you will get it worked out.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....