Need Fuel Pressure Testing Help

Tundra 2007 4X4, 5.7 L. Code P0305 misfire on cyc. #4 & 5 while pulling boat trailer, car shuttered, Check Engine, SVC Off, 4Lo lights all illuminate (vehicle was not in 4Lo). Pulled and replaced all coils and plugs with Denso brand. Notice #4 plug had insulation damage at electrode. Test drove all normal until rapid load placed on engine at 5K RPM, then car shutters, Check Engine, SVC Off, 4Lo lights all illuminated again. Thought it might be a fuel injector on #5, so move injector to another cylinder, problem did not follow. Turning off engine and restarting, engine runs fine until rapid load placed on it again. Wanted to check fuel pressure but found no Schrader valve on fuel bar. Tried to connect with Tee/Schrader valve at fuel feed line feed but found smaller diameter on Tee test kit then Toyota fuel line connector so no go. Is there a specific test kit that works with this engine or a another way to test fuel pressure. Could there also be another malfunction causing this problem with engine under load?

 

I also have a 2010 with the 5.7 and getting misfire on cylinders 7 and 8.... the issue comes and goes and I ruled out the plugs and coils. How does one check fuel pressure on these? Any help is appreciated.

 

Might be able to get some info from code scanner, by viewing live data.

Edit: I wonder if @Thrussn solved his problem. Sounds like same problem.