I have an 08 G37, it just recently started after problems when I start it. It will start fine, and run fine (if I stop at a stop light, idle will dip a little but come back up) but if the engine is warm and I've been driving, turn engine off, and start again while it's still warm, the car will dip so low it will either die or almost die. I basically have to give it a little gas to keep it alive. Any suggestions as to what could be causing this?