Hi, I’m Chris. Welcome and thanks for asking your question!
Have you narrowed it down to just one or two cylinders causing this?
Is it always this cylinder(s) or is the concern moving around to random cylinders?
Have you ran a cylinder compression and leak down test on every cylinder?
Have you done anything to address the lean codes?
One common issue on this engine is the valve seats getting crushed and flattened out and causing the compression to a be a little lower resulting in a misfire under certain loads. The cylinder compression and leak down test will tell you if that head needs to be replaced.
You then need to check and see if the source of the misfire is the lean codes. Low fuel pressure from a clogged filter or weak pump can cause both concerns. leaking intake gaskets or PCV or vacuum hoses can cause both concerns.
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