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 soI 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

Any help would be greatly appreciated thanks!

 

If the injector circuit passes the test from the ECU electrically, they will not throw codes.

With "modern" vehicles, it is best to have a scan tool capable of displaying live data so you can monitor to see if anything looks out of place while the engine is running.

As I am not that familiar with 2006 4Runners, I cannot really give any common things to check for.