rough idle/misfire, could it be the coils?

Hi, recently my 99 BMW 323i has been misfiring when starting up. It would make a popping/cracking noise under the hood, and then would stop. However, it does sometimes have rough idling, and after idle, it would have no power it would only go to 20 MPH, when the gas pedal is pushed down all the way. The no power occurs when stopped at a red light/ or slow traffic, not completely parked.

We checked everything from the coils, to the battery, to antifreeze, to the O2 sensors.

We changed the O2 SENSORS, the water pump, gaskets, washer reservoir, hoses, but this is for the cooling system....only.

Does anyone know what could possibly cause this? And, what are the potential solutions? Please, Help! This doesn't happen every time, but every so often it does...Usually everyday, and some times it runs smooth, other times it doesn't.

Again, another thread where codes would be most advantages.