RPMs surge slightly when at steady speed
Explanation - between 30 and 65mph while keeping the speed and rpms as steady as possible I can see on the TAC that the rpms rise by about 100 or so and I can actually hear it through my flowmaster exhaust. For instance at 40mph and 1400rpm I can see the TAC go up to 1500 then back down again this continues about every few seconds. At idle the rpms are steady. Above 70 I don't see this, it starts around back when speed drops to around 65. Neither the SES or check engine light are on. Anything simple I can check?
99 Firebird V6 3.8 automatic 149k