I was driving down the freeway and my G20 just lost power (no sputtering), then, as I pulled off to the side to exit it appeared to be OK so I pulled back onto the freeway. After another minute it lost power again so I pulled off at the next exit where I pulled over - the car seemed to be purring normally (so I thought maybe it swallowed a bad chunck of gas). I pulled back onto the freeway. Two exits later I could feel the power leaving again so I pulled off on the next exit. As I was driving down the road trying to get to a car repair place I had been to before it started losing power again. I drove on the shoulder surging then rolling repeatedly as the power went and came back. I made it to where I cut across to make a left hand turn - I was able to cut acroos to the turn lane, wait at the light and turn to make it to the car place. They looked at the car and found nothing unusual - they replaced the air & gas filter. No prob with injectors/firing. Still not resolved... HELP

I just had the same problem with my 2002 Q45 last night. It was driving normally then suddenly it lost power and was just idling in drive. I pulled over to the side where it started idling rough. After about ten minutes of rough idling, it started running normal again. It drove normally for about 5 minutes, then lost power again and started idling in drive again. After another ten minutes of idling it started running normally again. It did this one more time before I got home. Did you ever find out what the cause was?