i had the same problemo on my s1 for months,i replaced EVERYTHING,plugs,leads,dizzy, arm, cap, coil, fuel pump, fuel pump relay, actuator, checked all wiring, ignition ecu,
turned out to be a balyst (spellcheck that!) resistor. a small black box dangling by the metering unit with 2 real short wires popping out of it which join and disapear into the coil wiring. i robbed 1 off an xr3i from a scrappy as a 'might as well eliminate whatever that is' and it turned out to be a stroke of genius! try it!