Hi Tom, if the abs lamp is on, it will fail the MOT, yes.
If the coil pack was disconnected and reconnecting it resolved it temporarily, I take it you have disconnected and reconnected it?
If you have a shot engine mount then you will get a shudder, yes so maybe this is the cause of some of your problem. Driving a car with a shot engine mount will damage other things after a while. I know it sounds stupid but could you post a sound clip of the engine revving up? We may be able to tell if it is misfiring.
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