Urgent help req 2.6 A6 starting and idling

[muscle750]

My 1996 A6 v6 ABC engine, has recently been playing up big style basically it started with it idling at anything from 1000 to 1500 when hot and other times it would idle perfectly normal it would suddenly cut out when idling high and then re start with no probs, It went in to a Audi specialist who found no fault in the comp etc. Although he did find that the temp sensor for the ECU was more than likely the prob. Yesterday the car broke down it sputtered to a halt and refused to start when it finally got going it stank of fuel as if it was over fuelling and had flooded. I got the temp sensor and fitted it. The car seemed ok this morning until i just used it went out it again spluttered and very nearly cut out but it didnt, then it started idling high and tonight i went to the shop came out 5 mins later and again it refused to start took me nearly 15 mins to get it going again when it did it stank of fuel. It seems if you stop the engine with it idling normal it will restart ok if you stop it idling over 1000 it wont restart.
Any ideas before i send it into Audi and end up with a bill that will make my card bleed!