7.5 gen 2016 le (I know not a trd)

Hey guys im gianna! I drive a 2016 camry le..
Just reaching out to as many toyota forums as possible to try to get certain answers and i need all the help i can get. I am trying to reach out to new toyota forums im having a slight mysterious issue that not even some of my seasoned mechanic friends can pinpoint. I have 262,264 miles on my car. Never thrown a check engine light that isn't a gas cap pr purge valve issue. Had 1 misfire but that was because an ignition coil failed so that was quick fix. The issue is my car at idle with the heat on heat off ac on ac off parked or just at a stoplight and sometimes even while driving slow or turning the rpms drop to 500 and below and then it rinses and repeats the voltage also drops. I have had people just immediately say torque converter, but while driving with my people they said it can't be that the car drives and shifts fine. I have a new tensioner and belt on I have an injen short ram intake as well. The problem started happening before the intake went into the car so it was happening before that was put into the car. I'm also not leaking any fluids and I run synthetic oil only for my car and get my oil changed religiously. Also it seems to not be a vacuum leak we did the carb and/brake cleaner spray into the bay in certain areas test and nothing revved the engine. I'm just trying to reach out and see if anyone has any other leada