So about 2 weeks ago my 99 jeep grand Cherokee Laredo started having this problem. If I was going over 50 and pressed my brakes, even just for a second it would start to wobble or jerk side to side really bad. Now it's doing this every time I brake and it's bad enough that I've nearly lost control of the vehicle a time or 2. It seems to smooth itself out after a few seconds of not braking or when I press the brakes hard enough to stop rapidly. I can feel a slight wobble when I reach 45-55 when I'm not braking but that went away after my tires were balanced. Weights feel off so it does it again. However my question is what would cause my jeep to wobble so much and fast that I lose control of my jeep?
You will get this effect from warped front brake disks.
Disks can become quickly warped by getting them hot from heavy braking then driving though water which cools them quickly.
You will need to get the disks replaced.