I have a 2006 4.0 Sport, during my last drive on the highway the truck started running rough, the CEL started blinking and the traction lights came on - pulled the codes found p0300, p0301, p0303. Swapped coils to see if the misfire moved, nope still the same. I noticed heavy fuel smell and fuel leaking out of the tailpipe - so I pulled the plugs to check them. They all need to be changed due to age but cylinder one and three spark plugs were black(rich) and I looked into the cylinder and could see fuel in the cylinder - I also checked compression in all three of the cylinders and it was all
around 180psi so I am thinking it is a injector issue but wouldn’t I have a code for the injector?
Also notice gas went from 1/4 to 1/8 just idling. So it’s definitely dumping fuel
Also performed a coolant pressure test when cold and it held 20 psi for an hour.
And it passed a block test - so hopefully that rules out HG

Any help would be greatly appreciated thanks!

Start with the easy stuff. Check the wiring harness to make sure rodents have not eaten anything. Its that time of year. If i remember correctly toyota uses soy( not sure how far back in years it goes) to cover the wires so rodents like it.

Unplug the battery and let it sit for a few minutes, it might work.

If that does not work get a set of " noid testers" . They plug into the injector harness to make sure its operating correctly. You have to unplug the harness from the injector. If the noid light shows the electrical pulse to the injector works properly you have eliminated the electrical part and its possibly injector related.

Disconnect battery to clear the codes and see what it does.

Injectors are pretty common problem on the 4.0. Theres a few threads on here about it. Just changed them all on my Tacoma due to similar symptoms.

If you can, get them flow tested..

Edit... Just fully read your post on how much gas you used, sheesh. I just bought the Denso ones off RockAuto

I’ve checked the harness and it all seems good.

Yup it’s DUMPING gas

I’m almost at the point where I want to replace all the injectors. I might switch the injector to a different cylinder and see what happens then

I’ve cleared the codes with my scanner and I did a hard reset(battery disconnect) - same symptoms

I’ve pulled the injectors for 1 and 3 and they aren’t cracked or anything - going to get them flow tested this week.

Also just throwing out another thoughts and ideas...
my injectors were actually leaking at where they seal into the fuel rail. Like actually dumping gas on/into the V of the engine.
But if this isn't happening (going out on a whim here) maybe a bad fuel pressure regulator could cause the issues you are having ??

I haven’t check the fuel regulator - but there is no visible leak on top of the engine - I pulled the injectors and the seals were starting to crack - but no leaks - I think I’m going to just take them and have them checked.

*edit* after thinking about the regulator - wouldn’t that affect all the injectors, not just one?

Yes it would affect the entire fuel rail. So would the fuel pump if it's not putting out enough pressure. The fact that you are consuming fuel as quickly as you are makes it hard for me to believe that this is the case. However, the regulator is attached to the fuel rail, so I would just change it along with all 6 injectors. Mess with it one time