My Lumina's "Service Engine Soon" light came on as I tried to turn over the ignition. The engine turned over, however the engine seemed to be oscillating and shook the car. I turned it off, popped the hood. I couldn't find anything visually wrong. So I turned it over again, same idiot light and oscillation, however I noticed smoke coming from the electrical component up front under the exhaust manifold. This car is a 1996, w/ 155Kmiles and a new computer and 50K on the new trannie. I love the car and don't want to get rid of it, what should this be? Is it worth repairing? Is the smoke (like that of a burnt electrical component) related to the oscillation? I would appreciate any help you can provide. Thank you
1996 lumina, LS, 3.1L. We use only synthetic oil. I noticed the oscillation and idiot light together. the smoke was a couple of days later when i tried to trouble shoot.