Check your timing and make sure everything is proper. It could be the crank pulley. Also, check all the bolts that hold the pump to the bracket. When they are loose the car often surges
1.9 AAZ pumps have a tendency of eating the cam plate in the pump. This causes metal to get into the advance mechanism and jam it up. To test this you would need a pulse adapter or remove to pump and remove both advance covers and see if you can move the advance piston. Any air in the lines? Try running it off a Jerry Can to see if it still does it.