I have a 1997 Chevrolet Blazer 4WD 4.3L SFI 6cyl. It has very weak acceleration and I have recently started hearing a high pitch whistling sound that only happens when I try to accelerate. Also I'm starting to hear a gurgling sound near the front end when I am driving and sometimes when my vehicle is idle. Can anyone help with possible diagnosis?

 

possibly the cat on the exaust is plugged, when your going uphil do you have to hold the accelerator to the floor to move?