Alright fella's its been a couple of weeks since i had the limp mode issues. Since i have done the ECU full reset by removing the negative lead off the battery i havent experienced this problem at all.....touch wood. My fuel economy has improved and i get another 60-70ks a tank which is better than a kick in the nuts.
I spoke to my relo who is a nissan service mechanic and explained what i had done, when i thought i had reset the ECU by depressing the accelerator 5 times after turning ignition on ect ect. He told me this more than likely placed the ECU into learning mode where it monitord driving habits and adjusts paramaters to suit. He explained that the ECU uses "fuzzy logic" which from my experience in the electrical trade is when the electronics basically learns from its own experiences and adjusts itself for the next time an event happens. I had placed my nav into learning mode. Becuase i had towed my scissor lift after doing this it basically taught the computer that it needed plenty of juice andall hands on deck from a standing start to help pull the 2.5t up to speed. When driving without load the computer believed it still had load on the car and would have responded by using the paramaters it had learnt with load......this was the mosted probable cause for the limp mode.
So a warning to all......If you carry out the learning mode process by using the accelerator method IT DOES NOT RESET ECU be carfull that you do not have to tow any loads as the ECU will get confused and more than likely cause a limp mode event. Follow OldTony's method by removing the negative terminal lead off the battery. This method discharges all power from the ECU and resets it back to default, but beware that it will wipe all fault codes stored. I learnt the hard way but looks like i got out of it cheap.
Hope this of help.