Hello guys...new here but I've been lingering for years ( not in a creepy way).
Last October I purchased an 05 tC for my commute to work. Recently the car started to idle really low to the point it felt like it wanted to shut off, so I bought everything for a tube up... (spark plugs...belts...air filter...cleaned the throttle body...cleaned the maf and added a bottle of sea foam) reset the battery and let the car idle for about an hour....I thought the low idle went away because it was settling around 6-700 but after a day it dropped back down to 500 and still shaking like crazy even causing my dash camera to record everything blurry because of the constant shaking/vibrating..... what do you guys think is the problem?.....the car has under 100,000 on the engine.

 

Is there a check engine light on?
Do you happen to have an obd2 scanner to do some testing?

The throttle body is drive by wire and the ecu controls the idle through this.

Of that goes bad it can cause this problem.

But more checking will be needed

 

Cleaning the MAF sensor and a battery disconnect always solved the problem for me. I heavily sprayed the sensor with CRC electronic cleaner. The MAF sensor would get dirty from my cold air intake. The problem stopped coming back after I installed the stock intake.