I need some help with my 2008 is250 189k. Car will not idle when at operating temp and am not getting any cel now.

First the car hesitated to start periodically so I replaced the old battery.
Then I started to get P0171 and then P0174 running lean only when I would be sitting at a light/traffic/drive thru, so I replaced the upstream o2 sensor(denso from rockauto)
Thought that was fixed but still after a 30 minute drive and when I start it up again hot the idle bounces until it will die. I was not able to start it back up once when I let it die at a gas station. If I press the gas at all it will run fine, but will bog out if I let go.
I did a smoke test through break booster port in plenum and did not find anything. Did it hot and cold, nothing.
I bought a Launch x431 for Toyota/Lexus and checked live data, fuel rail was pressure was 3980kPs when the car was bogging out.
Is this the LP fuel pump? HP? The fuel pump resistor or a relay?(I checked the resistor with multimeter and was getting 0.3 and also tried to jump it and it didn’t not help the car stay running)

Hopefully someone can point me in the right direction, would be eternally grateful. I’ve fixed everything on this car since I got it in 2011 and would love to be able to find and fix this issue

 

If both banks were showing fuel trim, rough idle or stalling, I would replace the MAP/MAF sensor. Mine always had an issue running rich on short start up and since replacing no more issues, no more stalling. The other cause we/ve seen is a bad battery ground,.... but that was an extreme case of corrosion. Throttle body cleaning may help with the idle.

 

So I watched fuel rail pressure this morning on cold start. I got 13,000kPa for the first few minutes and then it went down to 5000-6000kPa while no on the gas and back up to 12-13,000 when on the gas.

 

I got an eBay denso map but it didn’t make a difference but I go have one on order from denso. Battery grounds are fine, California car. And throttle body is clean

 

I got a Denso maf from rockauto and tried it and had the same issue. Could this be a leaking injectior? I will be replacing spark plugs, cleaning injectors, and cleaning carbon and replacing seals this weekend.

 

Do you have any codes/CEL now?

 

nope no codes now. If I let the car die just the check engine light will come on until I turn it off and back on. No check vsc or ! Come up and scanners don’t find anything

 

Have you tried a battery disconnect?

 

yes have had battery off for hours while testing other stuff and still same issue. I’m in the middle of doing valve cleaning, fuel injector cleaning, replacing spark plugs, fuel pressure sensor, and valve cover gaskets.

 

Hi there,
Please try to find someone that you can borrow a mass airflow sensor and install it in your vehicle and see is you will experience the same problem

 

I bought a new denso from rock auto and it did not fix the issue