What is causing my Chevrolet Spark to take too long to crank?

I have a five year old Chevrolet Spark. My car was affected by flood around
this time last month. Since then, I have gotten my car repaired and have
tested driving around. But here are two issues I am facing with my car:

1. Car takes a relatively longer time to crank.

2. I am yet to drive long enough on top speed yet, but from what I have
observed, the accelerator is slightly not as responsive as it used to be.

3. I live in tropical climate and when I turn the car on in idle mode, there
seems to be water spraying from the exhaust for around twenty minutes.

But generally speaking, the car runs smoothly and all the issues I
mentioned above are when it is at idle or just starting. Again, I am yet to
test the vehicle at top speed.

What do you think is the problem? My mechanic has billed me for new
air/fuel filters and spark plugs. Also, I have run the car on idle for a
sufficiently long time and so I doubt it's the battery.

Is my mechanic lying about the changes? Or is there something else that
could be the problem?