have you checked that you're getting spark to the plugs? if not check, or have your friend check, the coil pack with a multimeter. if you are getting spark and the coil checks good, it might be a fuel delivery problem. i don't know how to check for that on fuel injected cars. i'm almost strictly old school carburated non computer controlled cars. i s'pose it could be the engine computer too. do you have a check engine light on? if so, does your mechanic friend have a portable code reader? he could hook that up and it'll tell you exactly what the fault code is.
good luck
mike