A faulty coil pack will cause two cylinders not to fire, but your car will still run. It will not throw a code.
What you have sounds like heat soak. You might need a Ignition control module, some auto parts places will check yours for free, or if you are so inclined you can check your own. This link shows you how:
http://members.fortunecity.com/slade...leshooting.htm
The other component subject to heat soak is your crank position sensor, and when the car heats up if your cps is faulty, your car will stall.