I found that my mechanical vacuum gauge 'fluttered' at low rpm, so bad it actually rattled and swung wildly over 30% of the gauge's useful range, at idle.
It wasn't so bad at first, but over time became
very annoying. I could pinch the vacuum line between my thumb and forefinger, which would damp the erratic signal without interfering with the valuable feedback the gauge gives me under part-throttle operations.
I solved this last night by installing an in-line
vacuum restrictor. My Metro uses 3/16" line and required Dorman p/n 47311. if you car uses 1/4" line, there is a different part number for that size.
It works like a champ
