Sounds like an issue with too much heat. I would try to associate the A/C with the car dying. The A/C also makes the car hotter than crap.
When your car is off, there is a lot of trapped heat under the hood. Your temperature will increase when the car is off. If it gets too hot in this manner, parts will begin to warp from excessive heat. The excessive heat could be making some electronics do unexpected things.
Running way too rich could be source of the extra heat. It will make the exhaust manifolds really hot. The manifolds are under the hood, so that heat will get trapped. Seeing how Ford decided to make these cars as hard as possible to work on, everything is squeezed really close together. Something that might help is a cooling system flush. You can get a kit and do it yourself for cheap and make a huge mess, or you can pay someone else to do it.
I think you would know if you had a blown head gasket. Usually, air will get into the system and will cause overheating all the time. Plus on top of that, there will be a crap load of smoke coming out the exhaust.
Please expain the click sound in more detail..
These are just some thoughts.. I don't have enough data to come across a good explination.. I would see about taking Ammco to court. $2,200 is a big loss, that could have bought you a good running car with a 2.3L that would have lasted a great while and better gas mileage... With some money left over
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Pete