1999 Rx 300...bouncing Tach Needle

[avc]

The tach needle will do random jumping and you can notice a slight sputtering from exhaust. No codes show up...any suggestions for trouble-shooting this problem.

[eugene.s]

If this happens after starting a cold car (e.g. after an overnight parking) and the needle starts @ approx. 1,500-1750 RPM and then, while the car warms up, it jerks here and there but in 5-10 mins overall goes down to approx 1,000-1,250 RPM, this is normal. Sputtering from the exhaust (if it's really minor) during this process should be rather normal, too. Otherwise, after you drive for e.g. 30 mins, the needle in idle should be somewhere below 1,000 RPM and stable (save for the time when A/C goes on, in which case RPMs will jump up). Is this your case?