Ok MIL light on so plug it in and read the codes to see what code(s) have been set., I suspect you will see Camshaft sensor codes which seems a common fault as these break down due to age they are now. If it is replace with oem sensors, cheap ones are a waste of money as they don't last long. Don't forget to find your volt meters and test the output your alternator is putting out. If it shows a good output at leasr 14.5 volts thats one less thing to worry about. Bad alternator would not have set the MIL light so camshaft sensors likely to be the fault, see what the codes set are.