Alright so I just bought a 2006 Dodge Ram 1500 with the 5.7. The check engine light started flashing the other day and started shaking really bad so I took I‎t to the shop and they said cyl. 4 has a mis fire so they put a new coil on I‎t and said it was fixed and the next day I‎t did I‎t again and I‎ts the same cylinder. What could be causing I‎t to keep throwing Mis fire codes on that cylinder ??? What else could be wrong. Also I‎t has new plugs