MIL light on & Get you home mode

Please can I have some thoughts on possible reasons for the MIL light coming on and staying on, and going into “get you home mode” at 4000 rpm max.

Its a N/A car with Lotus re-flash and TRD air box recently fitted.

The problem started on my jaunt to France with Pesky but didn’t always restrict to 4000rpm. Then when I came off the boat 5 weeks ago at Dover the light wasn’t on and I haven’t seen it since…Until Monday.
I am going to have it read as soon as possible but am struggling to find someone to fit me in.

Get hold off a code reader and get the codes off, this will help with finding the issues.

What is ‘get you home mode’? Not heard of that one before - which is worrying considering I am getting a fair few MIL’s recently!

Get you home mode in my case seems to be a restriction to 4000rpm max, which is fine on a motorway as it represents 80mph in top (ish)
Unfortunately I live at the top of a hill 1000 feet up on the Pennines, and it is somewhat embarrassing to be chugging up the hill with various “shopping trollies” pushing to get past

It has been diagnosed as Throttle Position Sensor, which I understand could point to either the an Assembly at the pedal end or a Throttle Body. The price of the first made me wince a little, the second made me faint.
Anyone replaced either to know which one it could be ? (S2 N/A dont forget)

There have been repoted issues with the pedal end on Seloc I think, not sure why though…

Toyota and Throttle Pedals hardly have the best rep!!