I've been searching everywhere for a resolution while continually spending money! I had a fuel pump put in about 2 years ago for a no start issue, (car had been sitting for some time). It ran fine for months and then I noticed when making a quick left turn it would stumble, not always just once in a while. The next little quirk came a couple of months after that while sitting in the drive-thru line at the local coffee shop in the morning the engine would falter as if wanting to stall but would recover and settle into a normal idle. That would happen VERY infrequently maybe once every 2-3 weeks. This has been the norm until about 2 months ago, I was having fun with a bit of spirited driving when suddenly it sputtered and went into limp mode. I pulled into the next available parking lot and opened the hood and looked for anything out of the ordinary. Everything looked fine, I shut it off and then re-started everything was back to normal. I didn't push it going home and it ran fine, checked for codes and aside from the usual heated O2 sensor code that's been on forever it had multiple cylinder misfires. Well since I just changed the plugs a couple of months ago during a service I figured it might be a good idea to change the coil pack. I popped in a new one and all seemed well for a couple of days, then the limp mode happened again! Same codes so now the hunt began. Every time something is replaced it's okay for a day or so the the stumble happens or limp mode. It's a 2004 R50 normally aspirated, and so far the parts replaced list includes; spark plugs, coil pack, fuel pressure regulator, battery(as a precaution, a couple of slow crank days) another fuel pump, and I'm sure I've forgotten a couple of things. When it doesn't act up it runs flawlessly, quick (and I've had many sports cars over the years), smooth running, I'm not sure where to look next! There seems to be lots of misfire complaints but this happens infrequently and no particular situation seems to trigger it. Any thoughts??