2000 GS 300, 155K miles. Driving at 65 on highway, when I turned the inside temp setting up to 80 while the A/C was on. Turned the A/C off. Check engine light came on. VSC dash light came on at same time. None of the controls worked including VSC. When I pressed the gas pedal, heard a clicking sound in the engine compartment, so stopped giving it gas. As car slowed, all panel lights came on and car lost power. All lights still working. When I came to a stop at the light, dark smoke appeared from under the hood. Car wouldn't turn over after that and had to be towed. One mechanic said I needed a new engine. He said the radiator leaked and the engine ran dry and overheated, damaging the head gasket. Being looked at now by another mechanic but I'm trying to get answers. Don't want the expense of replacing the engine. Thanks.