08 4.7 crew max strange fuel issues

I threw a lot on $$$ on this thing and still found no fix to my issue.
08 crew max Rwd 4.7
Was getting intermittent start the die and long starts. My Toyota tech buddy said it’s fuel pump. Before he confirmed it he strapped a fuel gauge to it and watched…. Would start around 35 psi but would drop to 15-20 and throw lean condition codes. That confirmed his suspicions . Replaced pump and now it hovers around 30-34 psi and still got lean codes. So now we’re scratching our heads. He moved the guage back to where a fuel damper is… whalah! Psi jumped to 40. That’s it! He replaced it and unfortunately didn’t fix the issue.
We ruled out the fuel pump control module because we jumped it. And it puts out proper voltage. and all parts replaced are oem Toyota.
Anybody else have simular experience???

 

What about plugs, coil packs, injectors, vacuum hoses and all the other stuff that helps the engine run?

 

New plugs new t belt
It runs
Just low fuel pressure after pump was replaced AND control module was bypassed

 

You replaced the fuel filter?

 

There’s no fuel filter. There’s a fuel sock on the fuel pump……it’s all new

 

Next time it does it, get out and loosen the fuel cap, see if it sucks air.

 

When it throws the code? It seems to almost always have the code in the background…. When does that mean on the gas cap issue?

 

When it dies or tries to die, leave it running if it will, or let it die, but immediately get out and loosen the gas cap. If it seems to be a vaccum, then you have some issues with the carbon vapor canister. A partial vacuum in the tank could be your problem.

 

If fuel has been addressed, then it's time to move to either a vacuum leak, MAF or O2 sensor issue. A lean condition would have me thinking is a vacuum leak, check your intake vacuum hoses and other hoses past the MAF sensor. O2 sensor check for open loop conditions which would mean that the sensor is failing.

 

But that wouldn’t cause low fuel pressure???
I got cyl8 misfire today btw