Chris's new build of an MX5 based car

[CTWV50]

As I am still at a loss as to the lack of power occasionally over 5000rpm I thought I'd hook up a gauge to measure the fuel pressure.



Went out to test it and low and behold the power stutter returned after 10 minutes of driving. Fuel pressure remain solidly at 40psi (3bar), after a little thinking as I was driving I thought this must be coil pack related then but then thought what happens if i turn the lights off during a stutter ( I have been driving around with the lights on for safety/visability). Well the car took off like a rocket when I turned off the lights and when I turned them back on the car started struggling again. Now is this coils, the alternator, or could the tiny battery be the issue. I'm pretty sure the battery does nothing really when driving other than charge, car always starts first time so does that rule out the alternator. SO coils then?!?!