Right a little bit of background 1st:- Polo 6N 1999 1.4 16v AFH with 76k miles. Full service in July with brand new throttle body fitted. Recently the rear box has started to go and although not noisey i left it a few weeks before i replaced it and last week put just a std cat back system on. However last week the polo started doing the classic dodgy throttle body symptoms with a high idle of 1100-1300 , holding revs between gears and when in traffic the idle will 'bouce & surge' erratically up 2k before dropping back once the car came to a standstill. Oh and in general my daily drive is a mix but i'm only averaging approx 27-28mpg
So yesterday i dropped the car in with the garage who fitted the new throttle body in July & FOC they checked everything over and reset the throttle pot via VAGCOM - picked it up lunchtime and the throttle body is clean, there's no fault codes, all the sensors etc appear ok and the idle was back at 900. Chatting it over they suggested the problem could possibly be CAT related - i was hoping it was a duff temp sender or such....
Now by the time i got home last night ALL the symptoms were back
I really would appreciate any help/suggestions on a fix as this is really starting to pi$$ me off now.....
Dan