Couple of niggles help please!

[JJ.]

Ok so I've been showing the old girl some love she's had coilovers, new wheels, cambelt, aux belt sorted but still needs more and I'm needing some help. It's a 1.8t '99

First issue, occasionally when first starting or sometimes idling she "hunts" not massively but I'd say 300rpm fluctuations, I'm thinking maybe a air leak somewhere/vac lines need replacing?.

Second, I've put leather seats in from a 5.5 and the plugs are different can anyone tell me which colour wire from the seat goes to which colour on the loom please?.

Third and most annoying EVERY single time I turn my headlights on I instantly get the stop brake fault message flash up and stay on continuously until I turn lights back off, obviously a wiring fault she has a tow bar fitted and I have disconnected the wiring to it and made sure there is no short/touching wires where that was wired in but now I don't have a clue where to look next!.

Thanks guys.
Jay