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