Danny,
Is it revving past the ~5200rpm mivec cut in point?
If cold the revs are limted to ~5200rpm (cut in point is different depending on whether it's a standard version or the RS version)-the temp sensor which you mentioned I guess is the one that controls this. If it revs past 5200rpm, I guess the temp sensor is not cutting in to limit the revs and is therefore not the problem.
Blown fuse, loose relay?
Is the car running ok otherwise?
I believe Aidan on here had a seimilar problem with his FTO mivec when he got it first. Think it was a vacuum hose or something.
http://www.fto-ireland.com/forum/phpBB2 ... ght=vacuum
Obviously if you could get it connected to a MUT reader that would be you best bet. Failing that I'm sure there is some way to read fault codes without it?