Car only starts when cold

My 1999 Hyundai Lantra faces a starting problem.

It starts perfectly fine every morning or whenever the engine has cooled after driving.

If the engine is hot and I try and start the car straight after driving, it keeps cranking but will not start UNLESS I use engine starting fluid/spray.

After using the starting spray it starts and drives fine.

However!! The car has recently just started to bunny hop while driving now, and has even stalled on its own as I was about to park it.

Any ideas ???

I have also had the spark plugs changed and I believe the fuel pump is running when the starter is in the ON position

Is the check engine light on? If not , it could be just the inside of your throttle body need cleaning.Or your air filter might be so dirty it is really restricting the airflow. Or both.

No check engine lights and brand new air filter. Have not cleaned the throttle body yet.

Have you considered the possibility of a defective coolant temperature sensor?