FR ko4ed limp home fuel pressure too high... HELP

Hey So my car is running stage 3 REVO and has been for about 6 months now, suddenly the car idles very poorly when cold so bad it will almost cut out it also has started going into a limp mode and will not go above 4000rpm there is no boost at all, I have the following fault codes:
P0088 Fuel Rail System Pressure to High
P0094 Fuel System Leak Detected

I also had a coolant temp sensor fault which i have now sorted by replacing sensor.
Ive check for leaks and cant smell or see anything.

My suspicion is that it may be a faulty map making it run poor or even a faulty fuel pressure sensor, your thoughts would be appreciated.

Thanks for your prompt reply, do you think it would cause rough idle too?

well if im honest I bought the car running poorly, and im now breaking it i was told it was running fine before. the car has a revo sps with it which i have played with but still no joy.

when you say vcd to log anything do you mean live data ie actual and specified data?