Does anybody know of a decent tach that I can either plug into the tach service connector or use under the hood to help set the idle speed? I'd much prefer a digital tach to do that instead of trying to guess what the RPM is by looking at my dash tach that doesn't have ANY marks between 500-1000 RPM.

Do the inductive tachs work well? There's several of em on eBay, and supposedly they work much like a timing light.

Sears has an "Engine Analyzer" that has a bunch of different testing functions, but the product description on the website isn't very detailed at all, and I can't tell from the picture how it hooks into the car to measure RPM.

Thanks!