I recently bought a 2006 Lexus GX470 (basically a fancy 4Runner) with 77,000 miles on it. When I start the car, one of three things happens…
5/10 times - starts normally
4/10 times - engine turns for 3-5 seconds before firing up
1/10 - engine turns for the 3-5 seconds but doesn’t start
Also, in the few weeks I’ve owned it, the car has started 4 times on it’s own if I do random things like lock the doors. As soon as you stick the key in or try to do anything to try and drive it the engine stops.
I did take it to a very reputable local shop and of course it did not replicate the behavior in their care. They discovered an aftermarket electronic system of some sort that was tied to the ignition. They pulled the power source from it just in case it was the cause.
Before I trudge down to the shop again, looking for best guesses and/or exorcism.