Got a crazy problem and don't know how to fix.

Occasionally my disco 1 won't start, the starter turns but the vehicle doesn't start.

The fix is just to pull my negative battery wire from the battery for a few seconds and then reattach and it will start.

Anyone had or know how to fix this problem?

Another problem is driving down the highway, it's as if the fuel pump turns off for a few seconds then comes back on. When this is happening, holding the throttle pedal closer to the floor exacerbates the problem while barely pushing the pedal it doesn't do it as much.