2009 stutters at idle/low RPM. Again.

[hutskob]

I have a 09 Altima 2.5L with 190k, CVT. About 6 months ago, I was on the way to the fuel station when it started stuttering badly. I thought I was about to run out of gas. I made it to the station, filled it, but the problem only got worse as I continued down the road. I stopped driving and took it to the shop 2 days later. The stutter would occur at idle, but the idle stayed at stable RPM. If accelerator was depressed lightly, it would get worse and power was limited. However, if I stomped it, the stutter would stop and I would regain power.

The shop told me my valves needed cleaning/replacing. A good amount of $ later, the car runs fine and has until today. On my way home today, it started again. Same exact issue. The idle is about 700, consistent but rough. The acceleration is sluggish and feels like a cylinder is mis-firing. If I floor it, it accelerates normally.

I already had made an appointment on Monday for an oil change and state inspection. I don't think another valve job will correct the problem, so does anyone have any ideas as to what this could be? TPS? Exhaust O2 sensor? I'm hesitant to spend another 1k+ to have this happen again in 6 more months.

Thanks for any ideas