is250 rough Idle

[alankehoe]

Does anyone have any idea what might be causing the car to idle rough, see details below.

Details

2008 Lexus is250, 120,000 miles / 200,000 km

Description

Idling rough when the engine is hot and in either drive or reverse. when in park or neutral idle is fine, see the video here https://photos.app.goo.gl/CuDuxKGNB64WwuuM7

Recent History

This seems to have started after the alternator was recently replaced due to failure, also worth noting that the air-con currently is empty of gas however I am not sure that makes any difference. Initial thoughts on the issue was that the crankshaft sensor may be bad but we have replaced that and the issue remains.

[madasahatter]

Clean the mass air flow sensor, also put some cataclean in the tank. Then give it an italian tune.

[Ishaq]

I do the Carbon Clean, every year as part of my service and it has helped me big time. I notice the car much smoother. Google carbon clean to see if you have anyone in your area.

Takes 30 minutes, I pay £60 (second car £30) so its worth it.

[alankehoe]

To conclude what the issue was here: 

After the alternator failed it was replaced with a spurious part which was faulty and surged when the engine was hot, this alternator since failed and was replaced by a Denso part. No problems with the car since then.

[Texas]

Thanks for reporting back with the remedy, and glad it’s all sorted. Just goes to show that when replacing parts to try and cure a problem you cannot be absolutely sure the new part is 100% good and this then sends you down another road try to fix same problem as you assume new part cannot be problem anymore!!!
Cars, Don’t you just love ‘em!

Note, it might be worth giving the MAF sensor a quick clean ( simple enough job) with some spray cleaner, as at your mileage if it has never been done it might make a noticeable difference.