Cylinder 5 and 6 are misfiring. Has good compression all around. Leak down test is good. Replaced the spark plugs, wires, cap and rotor. Routed the coil wire per tsb article. Pressurized the cooling system no leaks found. Pulled the fuel rail and tested the injectors on 5 and 6 to see if they are operating and they are working fine. The engine when cold wants to die and not run. You hold the gas down for a while and it stays running after a while. Replace Ecm and coil. When you pull off the spark plug wires to see if they are operating you get a spark all the way across. you can hear the engine run different when pulling them off the spark plugs, except for cylinders 5 and 6. They have good spark and waveform. You pull the injector wiring off those 2 cylinders and it makes no difference. I suspect a intake manifold gasket leaking but have never run into a problem like this before. Any help would be appreciated as a starting place that I may have overlooked.

 

Possibly the power splice that powers the injectors. Or bad injectors. Try swapping 5 and 6 to 1 and 2 to see if the known good injectors cause the same problem.