I've had an intermittent issue since I got my LS430 a couple years ago and that's a slight stumble when starting the car after sitting over night.

It's certainly not every morning, but it has happened more often recently which makes me think the issue might be getting worse. The issue is the car will sometimes die right after starting, and sometimes it stumbles but does catch and start with a higher RPM for a second or two.

After the car does start, it runs great, no problems at all, and like I said, I would say 90% of the time it starts no problem.

In looking through old posts, I'm thinking it might be a fuel issue (filter?, pump?) but not really sure...any thoughts are appreciated.

 

Try cycling the key a few times before you try to start it. This will prime the fuel system. It sounds like the system is losing pressure after sitting.

 

It's most likely the MAF sensor wearing out

 

Dont think so...got a new MAF last year trying to fix a low idle issue.

 

Well if you did replace it and you know it's a good part then make sure you don't have vacuum leaks.

 

A vacuum leak from a dried up, crumbling EVAP hose did that for me.
Could be a dirty throttle body (i.e. clogged idle ports) as well.

 

I cleaned the throttle body last year at the same time as the new MAF.

Vacuum leaks are next on the list...thanks