Hello again,
I have a 2004 Buick Park Avenue with 166,000 miles on it. I had a misfire issue around 130,000 and ended up replacing the coils, wires, and the sending unit ( I think that'* what its called). I haven't driven the car in over a month, and I turned it on yesterday and it drove no problem. However, later in the day today after I had driven the car several times, I started it up, backed out of the driveway, and it started running really rough, RPMs jumping up and down like it wasn't warm. The check engine light then appeared and I started smelling a strong burning smell, kind of like the smell you get after you light a firework. I pulled back into my driveway, and left it on so I could hear the exhaust note, and it was making a ticking sort of noise, hard to explain. I thought I could've lost oil while it sat, but I checked the dipstick and it read normally. What could my problem be? I couldn't imagine that I'm already misfiring again?!

Pull any codes, get back to us.

Did this fix it?

What is the sending unit really called in this case? There are various sending units in your car.

From the exhaust? From the engine bay? From the HVAC vents?

This plus the long slumber makes me suspect someone crawled up in there, built a nest, and chewed a spark plug wire or two. Have you looked around in there?

. . . and what Mike said: