I would be grateful for any suggestions anyone could provide regarding this problem with my car.
It's a 2000 reg Ford Focus 1.8 Zetec. On cold starts, the engine revs up to around 2000 all by itself without me putting the accelerator down (and it's not stuck on a mat or anything, I've checked). The revving becomes worse when I put the clutch down - it shoots up to 3500+. It reached 4000 last night, which is the worst it's ever got. Usually whent this happens, the engine gets to around 3500 and then it stalls itself or cuts out, and when I switch it back on the problem is gone. However, last night it didn't do that and just continued to rev - it was also very difficult to get it into reverse gear (it made the grinding noise you get when you try and change gear without the clutch fully down).
The car does it at traffic lights, and also whilst driving (ie, when I change gear when driving the revs shoot up when the clutch is down).
This morning I drove 3 miles without touching the accelerator - that gives you some idea of how bad it is. It's also very worrying in icy weather, as I brake against my own engine and it can be difficult to control.
The car's done this before - it did it a couple of years ago and I took it to a garage to try and find out what was wrong. They had the car for two days and didn't find anything (they didn't charge me, which was nice).
Any ideas? Thanks!