misses until it reaches 3000 rpm

Hi all, My forester turbo has an issue. When I take off under moderate acceleration or when I'm cruising and I put my foot down to accelerate or go up a hill it start to play up and it releases all of its pressure from the turbo and has no power at all. If I just cruise along lightly on the throttle it runs ok. Also when it gets just over 3000 rpm it drives ok , still runs at the same boost as before and has plenty of power.
I have just replaced the turbo on it but it was doing this before I replaced the turbo. I have had it hooked up to a OBD II computer and no codes come up. I have done a boost leak test and have not seen any leaks. I have also cleaned the MAF sensor. I think it could be leads or spark plugs. Has any had this issue before or know what's wrong with my car before I start spending too much money on my car?
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Gidday Jason

Take it to a competent Subaru mechanic, mate. Or an "old fashioned" mechanic who's good at fault diagnosis.

From my Batphone

Plugs & leads are always a good start, esp with a turbo. Also replace the fuel filter & clean or replace the PCV valve. Even if these are not causing your probs, they need to be done anyway :iconwink:

Do you know what the compression is like?