Check the basics, a compression test and cylinder leakage test may be needed to determine the basic mechanical health of the engine. There is a simple chemical test known as a "block test" that looks for the presence of carbon monoxide in the cooling system which would indicate a blown head gasket. A scan tool is needed to retrieve and or interrogate the computer in your car to see where potential problems lay. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online