Code P0607 occurs after engine startup?

So this can be one of the ignition coils, fuel injectors, or oxygen sensors that has shorted out

The P0607 code refers to an ECM/PCM Internal Circuit Malfunction.

I would clear the codes and then without starting the engine turn the key on and then run the codes again. If the code comes up start unplugging the ignition coils and repeat until the code ceases, you have found the problem, here is how to test the fuel injectors manually.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Did you run the codes to see if there were any stored? This guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please upload pictures or videos in your response of any problems so we can see what to help you with.

Engine control unit malfunction fault occurs after engine startup , some times it runs good for around 2-3hrs and sometimes after startup fault occurs and when the fault is present Rpm start fluctuating and accelerator pedal stop responding. I have switched ecu to another vehicle and it runs fine

I would try unplugging the primary oxygen sensors to see if that makes a difference, I have seen the heater element inside the sensor short to ground and cause this issue.