Hey Professor Scotty,

Thank you for your free services, I’ve learned a lot from you and am forever grateful. 

I have a Nissan Maxima 2012 SV with 215K KM and with Crappy Variable Transmission. Bought it at 165K KM from a dealer in Toronto, Ontario. (Bought it before I start seeing your videos) so kindda stuck.

However, I am maintaining the car very well. Babying it since I got it. Replaced the trans fluid at 165K then at 200K both times fluid came out clean no dirt or debris. Replaced 6 spark plugs and cleaned the MAF sensor at 200K. Car runs perfect no issues, but sometimes not all the time the RPM drops to 500 and shakes a little then back to idle and back to 500 and back to idle. Not noticeable for regular people, but I do. 

OBDII scanner have no codes. FT in live data are ShrtFT1 @3.1% LngFT1 @7% ShrtFT2 @2.3% LngFT2 @5.5% and fluctuating. 

Second question. I got the car in June 2018 and ever since the battery is running. I notice that the battery is weaker than it was. Do you advice me to replace it or keep it until it dies. Does the battery have anything to do with car’s electrical system when the car is running? 

Thank you in advance for everything.