Car Struggling to Start

With this recent heat wave my car seems to be struggling to start on certain occasions, sometimes it is fine and fire's up just fine.

The starter motor is turning over but takes 2-3 seconds sometimes for the engine to fire up, this has never happened before.

I do have the ktec induction kit fitted but no other modifications and the car is always run on 99ron fuel and has millers nanodrive oil in there.

Any ideas?