97 cavalier z24.

I have done a lot of different repairs to this car in the last few months. I got the car and it needed a water pump. replaced the water pump and drove it for awhile. replaced the rack and pinion, filled it up with gas, on my way home I noticed that I was having to give it a bit more gas then expected to accelerate. by the time I got home, it wouldn't rev up past about 4k. I thought that it may be the fuel filter so I replaced this. Did not change anything. The fuel pump seems to be pumping plenty of fuel but sometimes I do have to prime the pump a few times to get it to start now. Is there another fuel filter in another location? There is also I whistling noise now coming from the rear of the engine but can't seem to find the source of this. checked for vacuum leaks and normal things but have not figured it out.

I also let the car idle for awhile to see if the cat was plugged but it never got red hot.

Start the car up and spray water on the back of the engine till the whistling sound starts to change.