No as otherwise it would be overheating all the time, you say it's only when it's at a standstill but as your fans work it shoulden't be overheating, I guess when the fans come on it does actually cool down and they switch off again?

MSD do an uprated fan switch for both RS Turbo and Sierras but not Escort.

As I say the Escort one is actually far better and works like a modern setup with it being able to have the fans on at different speeds.

I would check the radiator isn't sludged up followed by a flush of the system, or you could try a replacement switch as the current one may be faulty but these very rarely cause problems. Some owners do use the Sierra ones as the Escort ones are hard to come by trouble is you then have only one fan speed and if you do make sure it's the uprated MSD one.

Martin