Turned out that the pedal assembly (TPS) was faulty.

I found that when I unplugged the throttle loom from the pedal assembly (with ignition off) and then plugged it back in again everything temporarily returns to normal. It was as if something resets in the assembly when you unplug and plug back the loom back in. I did also check for loose/faulty connections/wiring in the loom and plug but this was all good.

So its been 3 days now with the new assembly and no throttle issues infact it completely transformed drivability. There is good pick up from stand still and through the rev range in every gear. I did also replace MAP sensor (which I broke cleaning it) and upgraded to silicone intercooler hoses...so this would have also helped performance.

Thanks to all. Hope this helps someone else.