POWER WINDOW NOT WORKING WELL

2000 CHEVY ASTRO VAN, 70,000
SINCE I GOT NEW SPEAKERS PUT IN THE DOORS OVER A YEAR AGO I NOTICED THAT MY PASSANGER SIDE POWER-WINDOW DOESNT WORK AS WELL. THE DRIVER SIDE WINDOW WORKS JUST FINE. BUT ITS THE PASSANGER SIDE WINDOW THAT WILL GO DOWN SOMETIMES WELL, SOMETIMES A LIL AND WHEN COMING UP THE WINDOW ONLY DOES SO 1/4 OF AN INCH AT A TIME. AND DOESNT ALWAYS MOVE WHEN THE BUTTON IS PRESSED. SO I DON'T USE THE WINDOW. I WILL FINALLY GET IT UP A LIL AT A TIME THRU-OUT MY DRIVE OR BY REPEATINGLY TURNING ON THE VAN AND PUSHING THE SWITCH BECAUSE IT ONLY GOES UP A LIL BIT AT A TIME.