When I had my cluster out, I hooked a hose to the economy gauge and was able to suck with my cheeks and make it move through the entire range. It responds instantly. If your gauge behaves this way when removed, I would suspect a vacuum leak or possibly a partially blocked hose.

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-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition