My 850 GLT runs great, just had new head gasket done, new time belt, water pump, all of the PCV system etc. New spark plugs and wires and a new altenator. I drove it from Ogden Utah to Tacoma Washington and back without any issues until I stopped at a rest area near Boise. I left the engine on while I ran to the bathroom so my wife could stay cool with the AC on. I got back and the car had shut off on its own, tried to start it and after a long crank it ran, but very rough. I got it on the freeway and it felt great. It was about 100 degrees out at the time. Now every time its hot outside it wont last long at a red light or other longer stop. It works great in the evening etc, I'm at a loss please help.

 

mine was acting up when hot. put a different ignition coil in and haven't had a problem since