Engine 'surges' after long run

[Bill_H]

Any one any ideas on following?
4.0ltr Chim, after a long drive up M3 and all around north M25 car ran faultlessly, pulled off motorway and now driving at 30 mph - 40 mph the engine began almost stalling and then surging.
I had to give it a bit of welly, problem gradually went away over next 5 miles or so. But it made it difficult driving on Mway and then through built up area......

Any one any ideas - otherwise she starts and runs fine (apart from the common low down hesitancy).

[blitzracing]

The AFM's get really hot off the exhaust heat, could be the first signs of a failure.

[EGB]

Check and clean connections on AFM and the clip is in place. Have shielded mine with tailored alluminium sheeting. Throttle pot sensor check.
I have heard on other posts that a sign of AFM failure is brown stuff coming out of the exhaust.

Edited by EGB on Thursday 19th April 10:41