So I talked to a mechanic friend of mine and he said that if there was a weak valve spring the compression test doesn’t always reveal that.
He let me barrow a leak down tester and said to make sure the valves are closed on cylinder 8 and test it.
He said something is allowing more fuel into cylinder 8 and that he agrees with me that it does sound like a weak valve spring.
And he said that could most definitely be causing the rough spot im feeling.
He said it sounds like the spring is ok at idle and lower rpms but it starts revealing its self around 2500 rpm where the rough spot comes on and it could be allowing the valve to stay open to long drowning the number 8 plug in fuel.