I *may* be getting somewhere....
Traced the throttle loom behind the dash, stipped off the sheath and checked the cable. All good, no breaks. It then heads into a larger loom, into the engine bay and joins the main black plug loom. Still could not find any breaks but sprayed the area with WD40 anyway - After seeing some pic on another forum I am going to double check where the black plug loom splits into two.
I then removed the plug from the throttle potentiometer to check the connections more closely, all good again. I thought I would leave it unplugged and get some Nanocom readings. Started up and there was no EML light, idle was fine, until I knocked the headlight switch. Suddenly after 15/20 seconds of running the EML came on, no other lights. Just as it did when I lost throttle response over the weekend. Nanocom was reading the throttle as getting 5v, obviously no variation as the pedal wasnt plugged in...
So could it actually be the throttle pot? Despite where all the signs are pointing?
Either way whether it be the throttle pot or a break in the loom I have bought some trailer cable which I can use to run my own direct loom to the throttle from the ECU. If it works, then it was a break, if it doesn't its the throttle pot. Or the Crank Position Sensor...
Good news is I fixed my alarm mis-lock situation, it was the passenger side door switch cable shorting on the bulkhead. Found and heatskrinked. Also realised why the range on my alarm is so low, the aerial from the 10AS isnt plugged into anything..