So went back to the car yesterday and after removing a bracket I had already taken off, which supports the heaterbox , from its loom strap I managed to finally get the ECU out of the car. The connectors all look damage free as do all 154 pins of the ECU. It has a cover on it with four removable screws but the cover is well stuck/sealed to the casing so I am not going to attempt to remove it. I was wanting to see if there was any obvious problems with the electronics but it is out of my skill range to attempt. Has anybody had any dealings with a firm called ECU Doctors Ltd? They have been recommended to me by the firm who remapped the ECU. As the defect is so intermittent they have a service where they supply a matching ecu updated to your map from your own ecu to see if the problem transfers. This I believe can confirm if it is a board problem or its the map. If the problem is fixed then you can keep the ECU with guarantee or send it back and the fee for that works out as £70. If you keep the one they sent it costs £285 plus VAT plus £10 p&p. My theory is a intermittent problem caused by a dry joint somewhere on the circuit board. It is the only reason I can think of why the ECU does not "see" the reduction in rpm when the throttle was still asking for a higher figure and produce a warning.