Steering wheel wobble when letting off the power?

[Infectiousvrs]

Hi all, a bit of a concerning issue that's hit me this week. 

 

The steering wheel had slight wobble cruising at 70 and when I let off the pedal it rapidly dropped to 50mph ish and the wobble got much worse and is louder and harsher as you go down through the gears. 

 

My colleague out it on his ramp and the brake caliper was seizing on, so we added some grease and the slowing down issue stopped. However... When I turned my car off it rattled noitceably from the engine bay area and we couldn't source the exact location but he thinks it's gearbox area. 

 

I drove home after this and the wobble is getting progressively worse, so much so I can hear the vanity lights plastic surround above me shaking, and the road noise became quite load with an almost intermittent thud thud thud thud thud thud but the noise was pretty dampened. 

 

I've already soaked loads of money into this car and I'm hoping it's not an expensive fix although it seems like it might be. 

 

Any help is much appreciated, thanks in advance 

[xman]

Check the sub frame bolts