The car is running rough and is low on power. Feels like cylinders are out.

Reconditioned HP pump and new injectors were fitted.
The engine idled fine and free revved ok. Let the engine idle to warm up and then test drove.
After 1.5 km into the test drive, I noticed the engine knocking only under load and white smoke out of the tailpipe. This continued all the way back to the workshop and 300 meters away from the workshop when I loaded the engine up the revs took off. Took foot off the accelerator and the revs kept increasing. I turned the key off and the vehicle has not started since.