I looked through posts to find out if there was any other person who had this problem with their bike and couldn't find one so here goes.
First of all there is no pattern to the way the bike behaves. I have ridden over 100 miles before it back fired and then chugged to a stop and I have ridden about 40 before it did the same thing. After I sit for a while, maybe 15 minutes it starts up and runs fine till it does it again. The last time it happened I went about 40 miles before it stopped, got it started and went about 10 and it started and then about 1 city block. At that point I had it towed home.
I is a 2009 S40, has about 23,000 miles on it, a 2 year old battery and it had a fresh tank of gas last time I rode it before I had it towed home. I am in the habit of putting gas additive in the tank when I fill it.
I have since taken it to a mechanic who has had it for over 3 weeks and he seems to have no clue but thinks it might be electrical. I changed the oil about 1000 miles ago.
Any ideas would be appreciated.