Micra K12 2004 power problem

[bubba]

Hope someone out there might be able to shed some light on this weird problem.
It all started after a 45 mile run over a year ago the car all of a sudden started holding back and then no power, upon pulling over the engine would continue to run as there is no pressure on the engine, but the minute you applied the accelerator the car was going no where.
Switch the engine completely off leave for say an hour go back to it and everything is perfect engine runs as sweet as a nut and plenty of power.
It never happened again...
However its done this a few times and now all the time.
Soon as the temp blue light goes out showing up to temp, no power, giving the impression the engine is going to cut out but it doesn't providing you don't put any pressure on the accelerator.
I suspected it could be an Oxygen sensor but trying to find someone round here with a tester to test the upstream or downstream some of the garges I rang don't do this, and one was not available.
So I decided to order two Oxygen sensors and replace them myself I'm certainly by no means new to mechanics.

Firstly when the engine is cold there is tons of power and car runs awesome, the minute it reaches temp it starts to mess about, holding back, no power almost like blockage, however it certainly is not a blockage.
Pull over on side of the road wait until engine cools down say when the temp light is in cold (Blue) off the car drives totally perfect until it reaches operating temp.

Having no tester I decided to go for the downstream sensor as the upstream sensor looked as though it had already been replaced at some stage.
After replacing I road tested it and everything from cold was perfect plenty of power and then soon as it was hot (Blue) temp light off it starts messing around again.
I then before replacing the upstream sensor and when the car was messing about, disconnected the plug to see if there was any difference and it made no difference what so ever the fault was still there, struggling.

Any ideas would be a help in identifying what is actually causing this problem, what ever it is I totally believe is electrical, maybe another sensor someplace (MAP) maybe or temp related Temp sensor which I highly doubt.
I was a complete dummy could have saved myself a lot of work, when I suspected an oxygen sensor I should have disconnected one at a time to see if there was any difference so food for thought if you suspect.

 

[bubba]

Its a MAP (Manifold Absolute Pressure) sensor not a MAF (Mass Air Flow Sensor) Lots have confused the two even I did.
I intend to fix this fault because the intention is to sell the car rather than just scrap it,
So given the fact that the car runs without any issues when cold and plenty of torque and power there this has to be something temperature related.

There can only be one or two things now that is causing the car to lose power soon as its at op temp.
The MAP sensor is either dirty or faulty.
I am also going to change the temp sensor even though I am sure its not that.
I'm sure the ECU operates a closed loop system when cold which means more fuel mixture as with a choke on early cars back in the day, In that instance bypassing the MAP or something along those lines.
Once at operating temp there seems to be more air than fuel mixture going in, giving the effect I am currently experiencing, either a dirty MAP or one that is breaking down.
I could be totally wrong

I will remove the MAP clean that first see what happens, if no go I shall replace the temp sensor given the fact I have one on order.
Should the temp sensor not be the problem I will replace the MAP.
There is no management light lit when or before the problem happens, so I doubt that even plugging in a OBD2 U480 diagnostic tool is going to reveal unless say the MAP completely goes down.
Oxygen sensors are working fine so its not them they have been ruled out.
I recall only a few months ago taking this car on a long drive to the MOT station for its MOT, the car was ran for a long time at the MOT station and I drove it back a good few miles and the car never missed a beat even though this problem had happened a few times before but only after say 45 mile trip.
Now it starts messing about soon as operating Temp is reached, crazy, you might think.. but back then the outside temps was freezing as it was winter, the outside temps have now gone up so the problem is happening a lot quicker, not sure if that has anything to do with it.
Still using the car to nip back and fourth to the shops last used yesterday drives excellent.
Should the prob surface again which it's going to until I have time to sort the MAP just pull over switch off sit there and wait, cool down and then continue but only now for very short distances.
Frustrating problem but nothing else I can do.
I know some never report back once they found the fault as its probably taken you an age to sort it, but I will...