1995 DeVille Running Rough - HELP!

Sorry for the novel length - this is my first post. I don't want to scare anyone off, but I really love my car and need some advice.

(Also, it's a '95, but it doesn't have a Northstar engine)

Late last week my car started running rough, mostly when I’m giving it gas, after the engine’s warmed up. It will shudder on idle a bit as well. I went to get the oil changed and fuel injectors cleaned on Sunday (about a month earlier than my scheduled change), because I was down a quart and wanted to see if they could see any leaks. They said there weren’t any leaks that they could see, though the coolant was low. I refilled that yesterday (waiting until the engine was cool and filling it to the “cold fill” line), and I don’t think any has leaked out since I checked it today and it was fine.

When I got the oil changed they checked the battery and the print out said something about the battery being bad. I’m getting it replaced today, and I know it’s wishful thinking to hope that will take care of the rough running.

I opened up the hood and looked at the engine while it was running – everything seems to be where it should be; none of the pumps seem locked up, the pullys are running, the belt is tight (checked after turning the engine off, obviously!), and the fan is going. I haven’t gotten any warning messages on my dash – no overheating, or check engine, or low oil pressure or anything like that. I haven’t even gotten a battery alert, which happened when the belt broke and the battery drained.

Basically, it feels gunky. I really want to hope it’s the spark plugs or filters or something easy. Please tell me it's something easy!

Thanks for reading

~D

The first thing is to scan the computer for codes. I think your car has a self-diagnosis feature where you can do this without a scan tool.

Turn the ignition on, but do not start the car. Press the 'off' and 'warmer' buttons on the climate control at the same time. You should see some trouble codes come up on the information screen on the dashboard. Write the codes down and post them back here.

Thanks for the reply! I checked the codes, and for each option it said "NONE" or "no codes found."