Ok, here's the deal. 89 GTU, completely stock, 170k miles, new spark plugs.

My engine idles solid at 750rpm and still has very good power. Engine does NOT hesitate at all all the way to 7Krpm (Yeah, I am a wuss and haven't redlined it) but when sitting and idle I hear small erratic pops, Especially when its cold (cold engine, not cold outside).

The idle does not budge when this happens. Could this just be a jacked up cat? Or a small exhuast leak? I smell no fumes and the car just passed emissions without any trouble.

Not really a problem but thanks for any input

 

You're probably running rich at idle.

All our cars do that...at least the ones without aftermarket tuning computers/EMS's.