Daewoo Matiz engine surges when idling

Check all pipes / vacuum hoses for any leaks .Also inlet manifold .

did you change the items because they were faulty, what fault codes do you have

It failed the MOT on CO which is why I bought the new Oxygen sensor. It then failed on hydrocarbons, which it had passed previously. I had filled up with premium fuel and added some injector cleaner. It was whilst it was being tested this second time that the surging started. I was advise by a neighbour to change the throttle body (got one 2nd hand) but this made no difference. The surging only starts once it gets warm. Unplugging the 02 sensor and throttle body valves does not stop the surging (which is about 5 second cycle) so Its not caused by these. Have blown smoke across the engine and have not detected any vacuum leak. Pulling the pipe off the cannister solenoid makes it nearly stall so can't tell if surging stops. I'm thinking this might be the area to concentrate on?

I bought a diagnostic attachment for my PC from ebay which was supposed to work with a matiz but unfortunately didn't fit. I shorted terminals no.s 1 and 3 n the cars diagnostic plug and counted the flashing engine symbol on the dash. The code was 1500 which was to do with air conditioning. My Matiz doesn't have A/C.

Sorry that's the tube from the MAP sensor that I pulled and it is signals to the MAO sensor that I think may need investigation?