Q: My lexus sc 400 tunes over but won't stay running

With a 23 year old car with 200 thousand miles it really could be just about anything, so it’s best to start with the basics. Your car has very crude self diagnostics, so you may or may not get anything from that. But it’s worth checking for stored codes if you can get your hands on the right equipment. Check carefully under the hood for air leaks. any hose or fitting that allows air into the engine without passing through proper channels will cause problems and should be easy to fix. Fuel pressure is one of the next things to check, the fuel pumps don’t fail as often as the fuel pump relay, so if you don’t have fuel pressure, don’t run out and buy a pump without checking the circuit first. A few other basic checks to determine weather you have injector activity and ignition will help you narrow it down. If this is starting to sound like too much trouble, you can have a professional do this at your convenience by contacting your mechanic. They can send a technician to your home or office to check out your Lexus and let you know what it will take to fix it.