Guys I have a 99 Malibu with a 2.4 engine.This car has a 135k on it and has been a great car for us. Several days ago the car starting running awful as it would stall and hesitate very badly. It seems to be okay when you're on the highway but when you get in stop and go traffic it runs bad. I thought maybe we got some bad gas or water in the gas tank so I added some dry gas and fuel system cleaner but that hasn't helped. Today I cleaned the throttle body and although I put a smoke show on for the neighbors it didn't solve my problem. When it sits and idles it sounds like a slow chugging noise is coming from right under the passenger compartment and I noticed kind of a putt putt coming from the exhaust pipe.Could I have a clogged catalytic converter and how can I check.Also any other suggestions on what the problem might be are greatly appreciated.

 

Guys I forgot to mention that when I was checking out the exhaust coming from the car I looked under it and even though it was idling badly and sounded like it would stall,it seemed like the whole exhaust was shaking or vibrating an awful lot.Don't know if that means anything or not.

 

Check the coil housing those do go bad and will cause alot of issues. You will need to ohm the towers

 

If the exhaust was plugged, you woulnd't be able to get the car onto the highway. Like ktm said, check out the coils. With the car running, spray water all over the coil and the plug wires. If there is any stumble or stall, watch where the spark is coming from.
The resistance check that he is talking about is to use an ohm-meter, and probe the coil output and #1 and #4....there should be a reading of 5K -8Kohms....and do the same for coil #2 and #3. If all this checks out ok, there is a bulletin on replacing the spark plug boots

 

I know cars have ignition coils and what they call coil packs. Are they the same thing or different and which one am I going to check and where is it located? As I said before this car has been very reliable for us so I haven't had to work on it much so I'm not real sure what the part is,what it looks like and where it's located. If someone can walk me through this it would be greatly appreciated.

 

Any "check engine" error codes ?

 

The check engine light is flashing on and off.The car is running so bad I can't drive it to auto zone to get it scanned.Any tricks on getting a code by turning the ignition on and off or anything.

 

The chugging may be caused by a tranny noise or an axle bearing. You should also inspect if the coolant level is OK and there is no leak from your water pump as they tend to make noise when they fail. Other car parts to check would be your ac compressor or the tensioner pulley.

 

Running with the SES light flashing, will burn out the cat converter.