I have a 2001 Sable LS with Duratec with a problem I have not been able to figure out. Every once in a while the check engine starts flashing and the engine starts missing. The A/C also stops blowing cold when this happens. I read the codes and got "cylinder 6 misfire". Checked the injectors and found a bad connector. Replaced the connector and the injector but the problem is still there. Replaced the spark plug and the wire for #6 with no improvement. Switched coils with friend's Taurus, still the same. The codes I am getting are PO306 and PO174. Took it to our Ford stealership and they said they would have to 'get inside the engine' to check it out. 'Maybe a piston or a valve'. Could this be right? It sounds like more $$$ than I can afford. PLEASE HELP!!!

There are several things that is still could be, one is you MAF and the big one is a vacuum leak, whichcould be on your PVC line. I would check these first before I had the shop to "get inside the engine".