Ignition turns over but engine doesn't fire two or three tries

What is your question?

Sometimes it takes 2 or 3 tries before the engine fires. Usually happens every time I take the car out, so far I haven't been stuck. Other times engine fires on the first try. Engine seems to run perfect once it starts, no misfire or running rough. I've taken my car in for service twice but the technician can't replicate the problem so I get my car back unfixed. No noises or leaks. Thank you for your help! Bob

What makes this problem better or worse?

Happens both when the car is hot ir cold

How long has your 2013 Lexus GS350 had this problem?

Maybe 6 weeks