Car sputtering...please help

Car in question is a 1999 Oldsmobile Eighty Eight LS.

I thought this was a problem with the transmission, but I'm not so convinced that is the case now.

Here's what the car does. It sputters. You can feel it when you apply light throttle on any type of incline. However, it is MOST prominent when the car is in 3rd gear @ about 1500RPM: the sputter causes the car/engine to lurch badly. In this gear, when the sputter occurs, you can hear an ugly squeaky thrashing sound coming from the lower part of the car, sort of around the cat converter area; it almost sounds like the engine is misfiring. If I mash the throttle, or go to about 2000RPM, there is no delay, sputter, or anything else. There is no noticeable sputtering in 2nd gear and no sputtering at all in 4th gear.

I've been reading that this can be the fuel filter, a clogged cat converter, a weak fuel pump, transmission going bad, and sometimes not even any of those.

I should mention that it started happening in late December, and is gradually getting worse. Can anyone please offer me some insight and help on this? I would much appreciate it.

No quick answer here, a scan for misfire counts should be done, plugs, wires and coils are also possibilities.

I would check the coil packs... this is sort of happened to mine and then suddenly one day i was running of four cylinders.. but a full scan would be more conclusive...all i'm saying is that is sounds electrical

As MW said, there's no easy answer, but might as well check something easy.

With the car off, pull the plug wires one at a time at the coil pack and check to make sure there is no 'rusting' at their tips (inside the holes). Good luck

Mine started doing this too. Then my check engine light would start flashing. It would do that occasionally when it was raining. I didn't think anything of it until it started happening more. slowly I have been replacing my coil packs. Then it got to the point where I was smoking from under my car somewhere. I was thinking also of a clogged cat converter, but all the symptoms leading to these seem to be an O2 sensor going out.

Newbie, this post is over 4 years old......if you have a problem, you should start your own post......