Another high idle thread - after cluster swap

[Diseasel300]

Is the idle actually high, or is the tach just off? What I mean is - does the engine actually sound like it's running fast when the RPM is elevated?

On some of the later cars there is a circuit built into the speedometer that can potentially cause problems with properly returning to idle. Member "Stretch" has quite a posting somewhere on this forum chasing that issue down in his W201. I don't remember where I read his saga or I'd post the link. It may be in his epic saga in the Long-Term Build forum (worth reading just because!)