Loss of power in Megane 1.9dci 2001

Hi:
I'm not a mechanic, work manufacturing car subchassis. The problem is with my car. Please guide me where the problems can go.
Car: Megane 1.9 DCI of 2001. KMS: 230,000
Problem:
1) Loss of general power continuously for 10,000km
2) In an intermittent and random way, but always by road (more and more frequently) although it accelerates, the engine gives a thief, loses power even reaching at times 120km/h at 40 or 30km/h in a minute or two (it goes down from rpm Slowly, almost always from 2,000 rpm in 5th). It is easier to pass if I accelerate to the fullest, but it does not happen whenever I demand and sometimes it happens when I am very calm.
I stop the engine (it is not necessary to turn it off) I leave it at rest for about two or three minutes and again ok.
3) No failure witness is lit.
4) In Bosch they have put the clip (apologize if it is not the technical name) and there are no active errors, in menory, or anything abnormal. Nor did they see anything abnormal in the engine, or when the car failed after trying it by road.
5) The problem is daily, but after changing the strap of accessories, oil and all filters (500km) the car was perfectly for a week.
6) During the change of the accessories, the external water pump was broken and the entire refrigerant came out (the pump was changed, in case it has to do with the fact that it worked well for a week).
7) The car does not heat up, nor lose water, nor consume oil.
EGR valve (the 3rd), Flower, refrogramming of the switchboard, turbo joints, turbo tubes (2), catalyst (3rd), precatalizer, etc, etc, etc. new for 50,000km.
9) It seems that something better is going if Bardhal professional additive is thrown in the fuel for injector cleaning, but also fails (enough less times, even if it is random) I have repeated this in the last 500km.
10) The distribution is to change for km (90,000), but they tell me that it does not have to do (I want to wait to see if this has a arrangement)


due to a problem of loss of power (it was continuous and did not take 80km/h) and that the switchboard did not mark anything, I took it to Renault Zaragoza (retailgroup), the car hit more than 6 weeks in the workshop (I swear) and it cost me more than € 2,000 € 500 of rental car+ € 120 of périto (only then they knew what it was). So I am reluctant to start disassembling and change everything to see what fails. Take it to Renault I'm not going to do it.
The only option they give me in the trusted workshop is to disassemble ... starting with injection and review of electronic accelerator.
Thanks a lot.

Hi Chabier,
your report is quite complete, everything that had to be proven is already done, tell me one thing: have you taken a compression reading to the cylinders? How is the fuel and air filter? When fails what smoke presents? They are things to take into account. Luck.
Miguel

You have changed the flow?
If not much proves to clean it with the spray for that use.
If it still fails, it may even be the pressure ramp sensor. I don't think that is, but by power, it could be.

They took a reading and it was OK (in Bosch), but the problem is that it fails randomly and only on the road, so in workshop and in a vacuum it does not fail. And if you stop on the road (when it fails) to which you put the computer (which is what the Bosch workshop manager did) the failure has already been corrected, although the switchboard does not mark anything at any time.
Respect the filters ... are new. With change of filters and accessory strap it worked well for a week, but it is the same.
When he fails, no smoke comes out .... White smoke has ever left, but now nothing comes out.
If I have noticed for two days that the car presents the problem intermittently for seconds, that is, it is heard even in the injection that is unstable for one or two seconds and gets good at the time.
Thank you so much!!!!

Caudalimeter changed 50,000km. I go for the 3rd. Like the EGR.
The other times that failure felling the sensation was different .... Loss of general power (which has it) and progressive, I do not know how to explain it.
In the workshop I asked and told me (the Bosch workshop manager who tasted it) that the shots were not going with total roundness.
With what happens for two days, that in addition to what has already been described even when it is going well, it shows that the injection stops "blowing" for tenths of second or a second ... we are going to try a sensor or something ... I do not know it seems like a false contact.
It would make sense that the switchboard did not indicate if for example it loses the electronic accelerator signal ... if it were the pressure ramp pressure sensor ... should the switchboard mark?
Thank you very much to both !!!