I have a P0300 pP0301 and P0303 I did multiple test and I believe I have bad valves don’t want to tear my engine apart due to the timing is there someone who experienced similar issues also when I drive around 40 mph the CEL flashes and the car drives but I feel like there’s something that shuts off and after 30 seconds it opens and gives me a “boost” and the car accelerates and does it over and over again till i start driving less than 40 mph and going up hill does the same but around 25-30 mph the car is at 172,000 miles can anyone help me

 

Usually bad valves don't work good then work badly. They either work good all the time or bad all the time..Something is going on with the cyls on the passenger side or rear of the engine.That is where cyls 1 & 3 are located.
What would help is a good scan tool to watch the fuel trims and see what is happening.

We don't want to start throwing parts at it.
We need to know what is or is not working correctly.

The mileage is up there, however, there are a lot of high mileage engines running just fine.