should get compression check. possible may be loose spark plug or fouled threading. these engines have a shorter thread count which has caused several issues varying from vehicle(spitting plugs, spark plugs snapping during extraction, thread slots that are brittle and prone to cracking, etc).
Check wire connections at coils # 3 & 6 possible damaged, loose connector. Check for cracked spark plug insulator, same cylinders 3 & 6.
# 3 is 3rd cyl from front on pass. side, # 6 is 2nd cyl from front on drivers side.