Right, took it upon myself to check all the electrics in the car hoping to get to the root cause of that mis-fire - I hope there's something useful below...

Here's what I've found - all done with ignition off and ECU disconnected.

-All connections between sensor connector and ecu are 100%.
-Reading between pins 24 and 25 (ECU to ignition amp), I have 24Kohm, which is way above the 1000 to 1500 it should be.
-Pins 11 and 30 (ECU to TPS full resistance), I am reading 412ohm which I think is ok.
-Pins 30 and 17 (ECU to TPS moving contact), I read 437ohm at idle, 0 on full throttle.
Before you ask, I have also taken the TPS off to take the measurements.

Would I be right in assuming that there is a problem with my TPS sensor and possibly the ignition amp too ?

I have been experiencing mis-fires on wide throttle and boost. New leads and grp A coil didn't make much of a difference. Plugs are NGK9's, 800 miles on them, gapped to .65mm.

Thanks for your feedback. I will crack it (one day).