Lack of power in Ford Laser!

[Fair man]

Hi

Can anyone help?

My daughter has a KQ Laser which at operating Temperature has a distinct lack of power on take off.

When cold it takes off well from stand still, but once up to operating temperature there is virtually little to no throttle response until you actually get moving above about 60kph & around 3,000RPM!

The car has done 136,000 kms & I believe the timing belt was done at 100K mark.

My suspicions are - Spark Plugs, Injectors or Catalytic convertor?

Anyone with any suggestions?

Regards