This is my first time on a forum so go easy as I have very little idea what I'm doing!
I have resorted to seeking help after becoming aware my ambition outweighs my talent. I have a 2005 Cherokee crd which I have recently purchased (now regretting it!) and keeps going into limp mode and throwing an overboost code. Initially it was only happening very occasionally every 3 days or so. When I removed the map sensor it was blocked solid so I decided to replace it rather than just clean it. I thought this had cured the fault but a couple of days later the problem reoccurred. I have experienced overboost on a number of vehicles in the past and it has always been under full load where as this only seems to occur when you have come off the throttle or slow down to pass something. Performance seems ok although boost tends to surge slightly under hard acceleration and you can hear a slight hiss which sounds like it comes from the boost solenoid as it attempts to regulate the boost. Below is a list of what I have tried so far and I feel I'm no clutching at straws with little direction and need some advice.
Map sensor replaced
Boost control solenoid replaced
Vacuum lines vacuum checked and reservoir solenoid actuator tested
Barometric pressure sensor replaced
MAF sensor cleaned/ tried disconnected
Checked for boost leaks
Egr removed and cleaned
Variable vane turbo sent away and refurbished/calibrated

Please help as I now feel I may be missing something obvious!