53 Plate K12 Micra Kicks Down While Driving

We have a 53 plate K12 Micra which has started to kick down while cruising (not accelerating) at 65 - 70mph.
Background - It does have an intermittent indicator, brake light, side light & reversing light 'Christmas tree' type issue at the moment which is caused by a poor connection of the reversing light 12v terminal in the LH rear light cluster.
I read a post on here that a brake light / indicator fault can cause power loss issues co could it also affect kickdown etc?
I am going to disconnect the reversing light tonight to temporarily eliminate the light fault while I test drive it but I thought it worth asking in case the kickdown issue is a coincidence and is something else entirely.

Thanks very much :) Any help greatly appreciated!