Noise with PWM Motor Driving Circuit

I’m using the circuit of this question: Problem with PWM motor driver
The problem of the past question is solved using a 1200k resistor and lowering the frequency to 4 Khz: now I have noticed, using an oscilloscope to check the voltage on the motor, that there is a lot of noise that reflects even in thw PWM wave, that without motor attached is ok(last picture). I attach the picture of the problem and of the circuit (now the resistor value is 1200k, differently from the picture).
Anyone have any idea of the problem? thanks