1995 Buick Regal JUST WILL NOT ACT RIGHT!

Electrical problem
1995 Buick Regal Automatic 122900 miles

I BOUGHT MY BUICK A YEAR AND A HALF AGO AND IT HAS BEEN ACTING CRAZY ON ME. FIRST MY FUEL INJECTORS FAILED ON ME. I GOT THAT FIXED AND HAD TO REPLACE PRETTY MUCH THE ENTIRE FUEL SYSTEM. NOW I'M HAVING ELECTRIAL PROBLEMS WHERE IF I LET MY WINDOWS UP AT THE SAME TIME, MY RADIO WILL SHUT OFF, MY HEADLIGHTS AND INTERIOR LIGHTS WILL DIM, PLUS MY SIGNAL LIGHTS ARE RATHER SLOW AND TAKES A WHILE TO BLINK. AND TO MAKE MATTERS WORST, MY CAR STILL CUTS OFF ON ME, WHILE DRIVING! IT'S DONE IT BEFORE, BUT STOPPED FOR A LITTLE WHILE, BUT NOW IT'S DOING IT AGAIN. IT IMMEDEATLY CRANKS BACK UP THOUGH. I'M READY TO GIVE IT UP, BUT NOW IS JUST NOT A VERY GOOD TIME RIGHT NOW. PLEASE HELP!