SSS had problems where, after getting all 4 of his injectors cleaned and such, 3 of them leaked afterward. Maybe he'll post about it if he sees this thread.
My car sortof does the same, I think my injectors need attention. The car blows black crap out of the exhaust when you start it up after it's been sitting for a while, and it runs gluggy until I warm it up a little and give it a decent burst of throttle along a straight stretch of road to get a heap of air pumped through the engine, i make a huge cloud behind the car (prolly like 20c worth of petrol lol) but it runs fine afterward.
It is definatly running rich, so it's a fuel problem.