SBC383CID

I FOUND SEVERAL POSTS ON OTHER SITES THAT SOUNDED EXACTLY LIKE MY PROBLEM AND THEY SAID ALL THE CLEANING FIXED THEIRS LIKE MAGIC. I HAVE GOT 2 CODES 24 AND 31

MY 1992 SC400 WITH 66K WENT FROM RUNNING LIKE A DREAM TO A PIECE OF JUNK. IT FEELS AS IF IT IS MISSING AND HAS A CHUGGING EXHAUST NOTE. I HAVE CHANGED THE PLUGS, REMOVED AND CLEANED THE THROTTLE BODY AND BLADES(NOT DIRTY THOUGH) CLEANED THE INSIDE OF THE INTAKE (NOT DIRTY EITHER) RAN THE ENGINE WITH THE MAF DISCONECTED. REMOVED AND CLEANED THE PVC TUBES. BOTH COILS ARE FIREING AND ALL THE NEW PLUGS ARE GETTING FIRE AND ARE HOT WHEN I PULL THEM AFTER RUNNING IT. I HAVE ALSO RAN THE ENGINE FOR 45 MIN AFTER PUTTING LUCAS FUEL INJECTOR CLEANER IN THE TANK WHICH IS ALMOST HALF FULL. ANYONE?