Vauxhall Astra car cuting out

I HAVE POSTED ON HERE THE OTHER DAY SOME OF THE PROBS IM HAVING NOW IT HAS GOT MUCH WORSE NOT ONLY IS THE PS WORKING SOME OF THE TIME THE E WINDOWS DONT WORK ON BOTH SIDES THE SPEEDO DOES NOT WORK AND WHEN SLOWING DOWN TO A STANDSTILL THE CAR GOES TO CUT OUT UNLESS YOU REV IT A BIT I ALSO HAVE THE CAR WITH SPANER LIGHT ON ALOT OF THE TIME I HAVE HAD DIONOSTICS DONE AND THE ONLY FAULT CODE IS LEFT HAND WHEEL SENSER IN THE HUB THAT WILL EXPLAIN THE SPEEDO BUT NOT THE OTHER THINGS THAT ARE GOING WRONG THE BAT IS NEW AS IS THE ALT AND THE PS IS A REPLACMENT SECOND HAND PUMP IS THERE ANY ONE ON HERE THAT CAN HELP BECAUSE ITS DOING MY HEAD IN . ALSO I HAVE CHANGED ALL RELAYS AND CHECKED ALL FUSES WHEN I BOUGHT THE CAR IT HAD NONE OF THESE PROBS AS IT IS EX POLICE CAR