somewhat irratic idle/off-throttle

[unadilla66]

07 manual HB, 103k.
The car is relatively new to me. Couple things bothering me- my idle doesn't seem very constant/consistent. It moves around between 550-650. And on the highway, say if I'm going down a long, gently hill and only have a little throttle open it seems to.....hmmm, not exactly 'surge,' and its fairly subtle, but the engine doesn't feel as smooth and consistent as it should. Anything more than around 1/4 throttle and I don't feel it. Maybe 2 separate issues, though seem like they could be connected. Ideas...?

[tmontague]

The idle issue is normal and can be expected from a small 4 cylinder like the 1NZ FE. As for the other issue you wrote about, i'm not sure I completely understand what the issue is

[bairjo]

Try cleaning the Mass Airflow Sensor. Since you didn't mention any stalling, it may or may not be the problem, but being an 07 it should be done anyhow. It is very easy to do. I would do a search on here and you may find a thread on that. Otherwise there are many videos on youtube on how to clean one on other cars.

[valchrist90731]

Back battery or voltages regulator?

I had to put both in and the car feels better running at 14.6 volts compared to just running on just a almost dead battery.