Need help to repair rough idlewhen cold and engind codes that keep coming back P0170 and P1188

Working on a 1998 bmw z3 roadster with a2.8 engine and the check engine light comes on the codes are p0170 and P1188, when the car starts up cold it runs rough and when it goes into closed loop it smothes out and runs fine. The intake and vac lines were smoke tested and leakes repaired. New plugs, fuel filter and ccvv/oil seperator was replaced, idle air valve cleaned, air felter cleaned. Data on a scane tool first time the front o2 sensor read 0% at.92volts and o2 sensir after the cat read 99.2 at.96 volt, replaced the front o2 sencer and rechecked date and the voltage on the front o2 sensor started to go up and down as needed.79 volt to.98 volts and read 25% rear sencer stayed at 99.2 % the car still runs rough at cold idle. Maf was changed not differance. Air control valve was changed no differance checked fuel pressure with 3 different gauges fuel pressure was 44 to 51 PSI depending on what gauge was used. Tps reads 17 to 18 on at idle. With the reading of the o2 sensors is the fuel pump not putting out enough pressure. The car at times will have blacke smoke. Your help or answer on this matter will be very helpfull. If it is the pump how do you get to it.