VRS turbo issue

Does anyone have their turbo cut out sometines on their VRS petrol (remapped)? On three occasions, once after filling up at BP (Ultimate) and twice at Shell (V-Power), for the time it took to use up a full tank of fuel if I accellerate hard it would feel like someone had switched off the turbo. Only when I then turn off and on the ignition would the turbo come back, (until I accelerated hard again). Its almost like the ECU thinks the fuel quality is not up to the job and therefore cuts out the turbo as a safety measure. Out of about 40 fill ups or so its happened on about 3 of them, once I fill up again with say Tesco's Super, or a different Shell garage the car is fine. Could this be my remap being quite lean Air fuel ratio, so if the fuel is not up to the job it cuts out the turbo? Or do petrol stations sometimes fill their tanks with the wrong fuel, (ie standard instead of super)?