Ive owned the car for about 3 months now. Every once in a while the car would shake like it was about to stall but doesnt. Its a 06 is250 awd 68k mi. Heres what I noticed.

1. It happens only when at a complete stop.
2. Completely random. It wont happen at consecutive stops.
3. Occurs rarely, like one ever other week or so.
4. Idle stays steady, nothing abnormal
5. No codes
6. Goes away as soon as the car moves

Anyone know whats going on?

 

Carbon Buildup..

 

I had the same issue with my '09 is250. I notified a local dealer about the TSB but they said they have to test the car first and that if they didn't experience the shaking that I would have to foot the bill for the test. I don't recall the what the charge was but I passed. When my car was up for the airbag recall back in July of 2017 I took it to the dealer where I originally purchased the car from. When I mentioned the carbon buildup TSB they said they'd test of misfires which they were able to replicate so the factory okayed the repairs. I haven't experienced the shaking since.

 

Wouldnt the rpms be erratic if it was carbon buildup?

 

but only at 68k? I would imagine carbon buildup is more prevalent to high mileage motors.

 

The carbon is constant per say. Its likely a combination of factors like ambient temps, fueling, ignition advance, engine temps, load, warm up period and all that jazz that makes it shake random. When warm it runs in closed loop adapting to many variables.

Start by cleaning the MAF. If no help and the spark plugs are do, install new plugs and inspect for carbon build up at that time.