High idle and loss of power.. Suggestions?

[pillapow]

miles away from me so im not much help. judging by what your discribing i very much doubt its the maf. how dose the car rev underload. ie on the road. if theres no fault codes except for when you disconected the maf id say your looking at a mechanical issue but the generic code readers arnt always the best for picking up all codes. id check everything you can thats easy and free. is your turbo healthy. all boost pipes in good condition. youd prob get a code if one blew off. i did on mine. is there a blockage in the exhaust somewear. i once had a issue like that on a astra. it sounded like it was hissing when reved. once i loosened the bolts on the manifold to exhaust it reved normaly. these are just suggestions and i could be miles away. its hard to diagnose issues with out having the car infront of me. wrap up warm tomora and get stuck into it

Under load when fully warm it feels like there is the tiniest amount of boost, the "kick" isnt there anymore, normally, at about 25% throttle it will start to boost at 1800rpm and will start to pull there, then theres the hard kick at around 3500rpm, all of that is completely gone, its just one laggy powerband now with nothing of note, the exhaust is pretty much brand new, its a custom system with 200 cell cat. If weather is ok tomorrow, I'll get into it, I want to remove the intercooler aswell to inspect it, would the easiest way be to remove the slam panel?