mulla

hi my car is remapped by a reputable person but lately in having boost issues. The problem happens when I fill the tank up and drive steady. I then try to boost and only holding 6 psi.the tank goes past a half and I get boost again. This could be in my head.i have connected the green plugs together and the boost solenoid clicks I have also cleaned it out.i have blown through it and all ok.when boosting it runs 16 and pulls like a train.it is just intermittent what may be the cause.the car runs on Tesco momentum and runs about 345bhp.