Shuts down on highway after changing many parts

While driving on the highway, it starts to "cut-out" and eventually stalls. I have to wait about 4 minutes before it will start again. When I turn the key during this time, it rolls over, but won't catch. It seems as if the waiting time is getting longer and longer as well. We have replaced plugs and wires, pick-up, distributor cap. rotor button, thermostat, MAP sensor, and the oxygen sensor. Yesterday, after posting this, we have changed the coil. We thought it was fixed, but alas, tonight, on my way home, it shut down on the highway again.

We would really appreciate any help you can give us.

Stacey