My 740GLE is running poorly. The idle is up and down a bit (500 - 700 rpm)

The O2 sensor & cat converter have been replaced. The bothersome item is

a sound from under the car that resembles a the air coming out of a baloon

(squeeling sound). I believe its coming from the fuel pump. I did replace

the pump recently but the noise persists and the car runs poorly.

I also hear a click under the engine everytime the idle drops to a lower rpm. The rpm's slowly come up again to around 750rpm then drop

Let me know if anyone has any thoughts

I agree that you should clean the throttle body and the idle control motor. If the engine cuts out instantaneously, and then starts again, it may be the main or fule pump relay. We had that problem, replaced both relays, problem solved. Could a squeal under the car be some kind of blockage in the exhaust causing excessive back pressure. Try putting your hand near the tailpipe and verifying that exhaust is coming out.

Clean the throttle body and your idle control motor. Where does the click come from? I've had that happen on my car, it was(i belive) fuel relay behind the fuse panel. Does yours stall? Mine would fall on its face everytime it clicked (even while driving). I had to take it to my mechanic who proceeded to check the thing top to bottom and didn't find anything. However, he did change the distributor cap and the spark plugs, and shortly after that i swapped mass air flow meters with him, and my problem went away(or so i thought) Now my car runs lean and doesnt want to start when its cold. :::shrug:::

I havent checked my throttle postion sensor or my 02 sensor yet, but they're at the top of the list (and i know i have a dirty icm, i just havent had the time to clean it).

What year is yours?