I noticed the following symptoms:
1. every time I fill it up with gas, it does not want to start up by itself. I have to help her with the acceleration pedal. But it does this ONLY the 1st time I start it up after gas refill. The subsequent times she is fine.
2. when runs idle (waiting at a red light for example), you can see that it almost chokes (it starts vibrating slightly). In the past, it happened once that I was stopped at a STOP sign, wanted to go after a full stop, and it stalled completely.
Hope this helps.