running really sluggish, idles fine, under load, get misfire codes P0300, P0301, P0303, and P0305. Have changed the plugs, wires, coils, checked the timing belt (all good) checked for vacuum leaks, have found none, checked for the intake leaking, no leaks. EGR appears to be working properly. Please HELP!!!

 

I believe #'s 1,3,5is the front cylinder bank (rad side). If you're not getting an intake manifold vacuum leak (which should also show up on idle) I wonder if the problem could be a malfunctioing O2 sensor. There is one for each bank. I believe 1,3,5 uses Bank 2 Sensor 1?? You also might have a common fuel rail blockage for that bank that does not provide enough flow under load. Another possible could be a blocked exhaust pipe for that side, but unless you've crushed a pipe I doubt that would be the problem. Seeif toyomoho postsany ideas.

 

The last code number corresponds with the cylinder, thus P0305 is cylinder number 5, etc. The P0300 is a general code.

Given the number of cylinders effected the problem must be general in nature. As Pedro states low fuel pressure due to a blockage or other problem would effect all cylinders. Fuel pressure can be checked but requires installing a gauge. Low fuel pressure would not have a specific trouble code.

Other causes could be MAF sensor, coolant sensor, wiring issues, your sure the EGR is working. If the EGR valve fails to open when required the engine will run lean and can misfire.

What year and model engine, perhaps can provide some testing info.

 

i have the same problems on the back 3 cylinders and done everything you did I even replace the ecu and I still have the same problems yet I have look everywhere online for help even on YouTube I put in v6 and always come up the 4 banger so there no help there different motors so if somone no what’s wrong please tell me cause I have checked and replace everything I can

 

That really sounds like a fueling issue under load. Take the fuel system for that side of the engine apart and clean it all out, reinstall, and see if that fixes it. If not, it's probably a lying sensor somewhere.