I've had some serious engling problems for a while now. It's a 3.8 Liter V6 push rod engine in a 1996 Mustang. First I blew a head gasket because of a collant clog, causing coolant to get into the exhaust and cause a misfire on cylinder #4. I replaced the head gasket, and it ran fine, but after running for a while (staying cool, no misfires, no coolant leak) it stalled. When I turned it back on, there was a misfire on #6 and a rattling sound that sounds like the timing. If anyone has any ideas on this, it would be appreciated. Why would the timing just fail, or could the sound be something else like preignition? It makes the noise regardless of temperature.