Wow, this sounds like the same problem I'm having. I was driving near mission bay 2 days ago and the car suddenly lost power, it ran **** like it had a vacuum leak. I checked for vacuum leak and it's all sweet. I then opened the bonnet and sounded like it wasn't running on all four cylinders. I checked all the spark plugs they were ok, then I thought it might be a injector issue so I unplugged the injectors one at a time and the car would sound different except for cylinder 1. When I un plugged the injector for cylinder 1 it did nothing unlike the rest of the injectors where it did something. I changed the coil pack for cylinder 1 and changed the injector still the same issue. I did a compression check and the readings came 120 for the rest of the cylinders except for cylinder 1 which was 110 which I think is okay still in the range. The car didn't chuck any check lights.