Got a PO353 and a PO356 what does this mean on 1999 Ford Expedition

Changed Coils all 8 and spark plugs Didnt have this problem before Also getting a misfire

by in El Paso, TX on March 29, 2013
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2 answers 3 comments
ANSWER by , March 29, 2013
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).
COMMENT by , March 30, 2013
Thanks it was one of the spark plugs and one of the connectors Thanks again!!
ANSWER by , March 30, 2013
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.
COMMENT by , March 30, 2013
  Thanks it was one of the spark plugs and one of the connectors # 3 Thanks again!!
COMMENT by , March 30, 2013
Cool, U welcom. We try!