Z axis stalling

I have built a bespoke printer which uses the standard twin NEMA 17 stepper driven lead screws for the z axis powered from a RAMPS 1.4 board
I can perform G28 and G29 commands and the machine behaves perfectly with all the axes moving smoothly.
However after a G28 and G29 I have troubles on the Z axis with a G0 command.
Both motors start moving correctly and then stall, juddering in a single position.

If it was not for the fact that the G28 and G29 operations work perfectly, I would have suspected a hardware problem, but I remain mystified.
Looking around the forum I have seen items about stalling and adjusting the drive current, but surely, if this were the problem then the G28 and G29 would not work smoothly.

Any help appreciated.

For my main printing I have a Prusa i3 Mk 3S and a Creality CR10s5 for the bigger stuff.

your z max feed rate is to high. 5 in the example below, but most should be 2 or 3, depends on what your lead screws are.

/**
 * Default Max Feed Rate (mm/s)
 * Override with M203
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_FEEDRATE          { 300, 300, 5, 25 }

when homing it uses a slower feed rate, so yes sometimes your stepper driver current setting can be the issue now allowing for faster feedrates

Edited 2 time(s). Last edit at 09/28/2019 07:06AM by Dust.

Thanks - such a simple solution when you know how.
Shows that I should not have made assumptions about G28 verses G0.
The default entry on the version I downloaded - I took a fresh cut about a week ago
DEFAULT_MAX_FEEDRATE {500,500,100,10000}

Thanks again