Potentiometer fault, won't fix

Urgh. 1999 Freelander, had a problem with engine warning light coming on and revs suddenly dipping, also at times over revving. RAC and garage tested and said potentiometer (thought it was as had this problem before, and was sorted by new potentiometer).

I sourced a 2nd hand one, had it fitted, but fault was still the same. Thought possibly the part was faulty, but had yet ANOTHER one fitted, and the fault is STILL THE SAME!

*weeps*

Any ideas?

You talking about the throttle potentiometer? Needs proper diagnostics with live data to look at throttle operation.

Thanks, going in garage (again!) on Monday!

If petrol try squirting WD40 into the idle control valve.
If diesel burn it.