New car loses power

Looking for advice,
My new to me S4 went really well, once I got it home I scanned it and found some codes, both lambdas, coolant temp sensor.
I cleared them to see what would come back.
Nothing did for a few days. But it had lost its main power output.
The car is mrc stage 3 and had lots of power. Leaping forward with slight touches of the throttle when I pulled away. It just wanted to go.
Then it started to lose more power over the next couple of days.
Then I got an issue with the bank 2 EGT sensor short to positive or open.
I cleared the code, the learned values and calibrated the throttle body.
Car was running really rich, loss of power like the timing was retarded, and occasionally it would harshly surge off and on during acceleration.
With a bit of research I found out that soldering the pins inside the egt was a possible cure.
Well yes it seems to be. No more fault code and no rich smell.
It was difficult to calibrate the throttle body after I cleared the codes and reset the learned values as I wanted to start again from a clean slate.
It took a few goes to get anything more than error from the TB.
I ended up starting the car, switching it off then it calibrated ok.
Now it's been a few days, I still have no fault codes, but the power is still down. The boost gauge fitted still goes up to 22 but the the previous seen 24.5.
I don't think that the gauge is calibrated accurate, it doesn't achieve full boost as early as it did. I logged some bits last night and hope that I can add the pics of them.
I have no idea how to resolve this. Please please please help.

I suspected that after sleeping on it.
The last time I tried to make a boost leak detector for my TT I thought I'd killed it. About a litre of oil poured out the back. I had a fog machine. I never found the leak. The TT still doesn't go right.
Is there any other safer method?

desertstorm said:

I am not sure if it is related but I would check the alternator as well as the battery voltage is well down. Should be around 14V.

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Indeed, the dash reports it at 14. I need to check it with a DMM. It could be a bad earth on something.

desertstorm said:

Don't know what the layout is with your car but there is usually a main power relay for the ECU and this may have an issue. Or as you say could be some kind of loose connection / poor earth.

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It's due in to MRC on Wednesday for a cam belt. I've just sent them the pics and pointed it out. Thanks for bringing it to my attention. I guess that alone could cause a weak spark, loss of power.

I've tried. The files to large. I've used my phone and trimmed then the format didn't match. I then screen shot each one and still the upload file is to large.
The forum image limit doesn't match today's smart phones.