Nissan 300xz 1990 TT Speedo

Hi,

I'm having a problem where sometimes the car speedo is not increasing much, while this happens sometimes the car will not change gear (Automatic) but if I put hold on it will change into second also sometimes the steering gets really heavy after a while things start to work again including the speedo. This happens 3 out of 5 times of running the car. Any help would be much appreciated.

Thanks