Engine Performance problem
1997 Toyota Rav4 4 cyl Four Wheel Drive Manual 115000 miles

I have a toyota RAV4 P reg, on idling the revs are very high over 2000rpm. It has now started to cut out after high revs and then slowly dropping until it cuts off especially when in traffic. Seems worse after Braking, when clutch is down. Thought might be the accelerator cable but now not so sure. Any help would be much appreciated.