Okay. Next thing then is we need to find out what the o2 sensor data is showing.
Basically, I suspect it is going to show that it is lean and trying to compensate for this.
This means the o2 sensor is telling the PCM that it is too much air in the exhaust and so it adds fuel. Then it starts to richen, and it backs it off. However, due to it having this lean condition you get the surging when the fuel is adding and then pulled away.
Then we need to put a vacuum gauge on this intake manifold and see if we have an intake valve issue.
By doing this we will find out if the intake valves are hanging open which will cause too much air to come into the engine and lean it out.
I attached charts below that will help with figuring this out.
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Saturday, April 9th, 2022 AT 7:09 AM