On starting, gas motor very rough idle, then smooths to normal

What is your question?

Just started last night, the gas motor came on in town, and it made the car feel as though I had a flat tire. Each time I start it now, it runs very rough for a few seconds up to about thirty seconds and then smooths out again and runs normal.

What makes this problem better or worse?

Temp does not seem to matter. Can't hear anything leaking

How long has your 2010 Toyota Prius had this problem?

Since last night