This must not be a very interesting problem. No responses so far. I will tell you that I have changed the air filter, checked the voltage to the fuel injectors, had my wiring harness changed (within the last two months). The problem just seemed to appear one day. What is confusing is that it only happens after the car has been run awhile, but never when the car is cold. Cranks and idles smoothe in the morning, or after it has sat (cooled down). I'm going check (with my limited knowledge) the power stage, and change the plug wires. What might be a concern is that my distributor failed about a month ago and I replaced it with one I bought off of ebay as a spare (the seller said he had only had it in his 740 for about three months before the car got totalled from a rear-ender). So I am now wondering if it might be a faulty distributor, but I am also thinking that if it were the distributor it wouldn't make much difference whether the car was cold or hot for it to misfire or idle rough. But then, what do I know? . . . should I come across a solution though, I will definitely post it for you.