yes i have several times . forget all the other repairs , i tried them all, you looking for head ache .
send the head assembly out and do a complete rebuild with valve job & clean up your intake .
new set of spark plugs .
Carbon build up is usually the most common cause .
after the rebuild head and repair, only use high octane gas .
Let me know if you need anything else on it ,just reply back here & we continue
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