My 88 740 turbo (auto tranny)idles absolutely smoothly when in gear. The idle remains smooth even when stuck in traffic or waiting for an extended period of time at a traffic light. However, if the tranny is shifted to neutral, within 30-45 seconds, what seems like an engine miss appears. Idle doesnt change, except there is a momentary drop concurrent with each miss, there is no hint of a stall or other problem. Just a miss. Its been doing this for years and hasnt gotten any better or worse. Lots of stuff in both the ignition and fuel injection systems has been replaced because of other unrelated breakdowns and problems but the engine miss in neutral remains. Any ideas.? All susggestions cheerfully accepted.