I have a 07 a4 2.0t quattro cabriolet auto with about 87000 miles.

Twice in the last few months when I have tried to start it goes up to just under 1000 rpms, runs real rough for a few seconds and then dies.
Repeated attempts to start i get the same result. It always fires but wont run for more that a few seconds. Seems like not all cylinders are firing. Runs very rough till it dies. Fluttering the gas pedal doesn't seem to help.
After may attempt i was able to get the rpm's up to 2000 and engine smooths out and idles normally. Restart at that point is fine.
No check engine light when this happens.

Timing belt was done about 3 months ago.
New coil pack and plugs 2 months ago.
Replace diverter valve and PCV last weekend but the first time this happened was before this.

Any help would be greatly appreciated.