as said check for air leaks and if it is mfi setup an airleak on mfi is a nightmare
but i would check the co2 as your new engine is going tobe fresh and breath different to the old one so could be co2 related
i would start by getting someone to set the car up, if you have a co2 tester (halfords do one about £75 ) see what the car is as it idles then take it from there at a guess i would say to high only coz i have been there
could be worth a try if you know its all piped up properly and all electrical connections are tight and clean
mark