P0174 P0171 Cylinder Misfires on Warm Starts

I've been sleuthing this too lean air fuel mixture code for over a year now on my 2006 Tacoma, 191,000 miles. On warm starts only I will have cylinder misfires and the truck has died multiple times after startup. I've let it sit for a couple hours then no issue. It's not every warm start, but most times it starts sluggish. Usually after driving for 20-30 minutes then starting it back up 10-15 minutes later. Cold starts in the mornings, never have had an issue. I've checked for vacuum leaks and it tests fine for that. My next best guess is injectors or fuel pump. Anyone else with similar issue? TIA. List below of what I've replaced so far.

• Ignition Coils
• Spark Plugs
• Cleaned Throttle Body
• Cleaned MAF Sensor
• Manifold Gaskets
• PCV Valve

 

I had this same engine codes but no misfires, roughly 180,000 miles and it ended up being the fuel filter. Cleaned my maf, throttle body, etc and nothing fixed my fuel trims until I swapped the fuel pump. If you've already ensured no vacuum leaks then my bet would be the fuel filter/pump.

 

Have you checked fuel pressure (should be 41 PSI)?

You have to tee into the line with a gauge to check it.
The best spot to tee in is under the hood where the lines connect.
You need something like this to tee in.

$35 BETOOLL Fuel Pressure Test Kit 0-100PSI with 9.497.896.30 Fuel Line Fittings

https://www.amazon.com/dp/B07LF26ZTJ

 

I had a similar issue on a Scion. When cold, it ran fine. After being driven then parked for 10-20 minutes, it would start up with a miss on cylinder 3 and the CEL would set. Let it sit for several hours and it would start up and ran fine. It turned out to be injector #3.

The resistance would be in spec (13.5 ohms) when cold. When warm up, the resistance would shoot up in the hundreds of ohms while the others remained in the tens of ohms.