Hi, are you yet satisfied with the performance of the car?
I have (or had, i hope!) the very same problem.
I also drive the '99 2.0. The problem has been now for around three weeks, coming and going.
And like you say. When the engine is warm, at low revs, like driving in town it could be a real pain to drive, but out on the roads it's a little to nothing.
Today however, I decided to install a new MAF, like mentioned several times in this and in other threads. And when doing that I had to take a closer look to the hose between the MAF and the air intake on the engine (as in picture).
It was wired with duct tape, done temporarily at a garage one year ago because the service guy found a "crack" in the hose.
Today, unveiling the duckt tape, we found the "crack" had grown to a large hole stretching across the whole underside of the hose.
We rewired the hose, this time with electrical tape, and O M G now she runs like a dream!
We also changed the MAF, but I will replace the old one tomorrow since I'm pennywise and didn't buy an original Bosch. Or I could now use the £170 I saved to get another hose.
I really hope now that this was the problem and that she'll stop hazzeling me.