2001 Rough idle, CEL and Trac light on

[PBZX3]

This is my daughter in laws car. The rough idle, check engine light and trac light all happened at the same time. She was in a parking lot and drove over a speed bump when all the problems started. The check engine light flashes when driving above 25mph. It's on solid at idle. I found the EVAP purge valve plastic nipple was busted off so I replaced the assembly. I was totally surprised when this had no effect on the symptoms.
I'm having my son bring the car over tomorrow so I can get a better look at everything but was wondering if anyone here has had anything like this happen to them. I find it strange that the car was running fine and then has all these symptoms after going over a speed bump.

[gmtech1]

The traction light and cel light came on because of the rough idle/misfire. The evap system will not cause a misfire. The PCM is located inside the r/f fender, the inner fender will need to be removed to access it. It's possible there is a problem with a connection in there that was aggravated by the bump. I would look at all the connections and grounds, anything loose. Should also have the code read to beb sure what you are after.

[PBZX3]

I tried to read the code with my OBD2 reader but got a message that the code could not be read. I've never had that happen before. I did notice the wire from the battery neg. to the chassis was very green at the point where it connects to the battery tray. I'll have to check that as well tomorrow. I wish it wasn't so cold or my garage had heat.

[gmtech1]

You may try running it by Autozone, or a place like that, and see if they have any luck on the code.

Yes, a heated work area would be nice...or a 70 deg day!

[PBZX3]

So I hate it when people don’t come back on here and tell everyone what the final fix was to their problem. I am not going to be that guy.
I originally said this all started after going over a speed bump. Turns out the cars been running crappy for a couple of weeks. I checked the spark plugs and number 3 plug wasn’t firing or at least was black like it wasn't firing. Swapped plugs 3 and 4. Cylinder 3 still wasn’t firing. Put in a new coil pack. No change. Put in a new ignition module on the coil pack. No change. Scratch head. Replaced fuel injector for cylinder 3. Car runs good again. Thanks for your inputs.