How can I fix my stalling Clio. ?

Renault Clio year 2001, 1149cc 8 valve petrol. The car starts first time every time even after stalling. The car intermittently stalls when coming to rest after depressing the clutch. When the clutch is depressed the rev counter drops way below 500 and sometimes recovers, sometimes dose not. The normal journey for the car is 3 or 4 miles however yesterday it went for a run of 16 miles, after about 10 miles the stalling occurred when stopping. There was also a strong smell of stale oil in the cabin although the engine does not use any oil. I am really stuck. The Renault Dealer came up with nothing, the local garage came up with nothing after being on an analiser.
Help would be welcome.