Buick Repair Questions? Ask a Mechanic for Answers ASAP
Extensive internal engine damage. You will need to find a new engine and a good mechanic. Sorry to break the news.
were you able to pull any trouble codes?
besides the misfire codes?
You have introduced a few variables into the rough running equation. So the engine got low enough on engine oil that it stalled. Something seized up. It cools off, you add oil, it will run. But, it misfires. These engines were known for timing chain and camshaft issues. Low oil will cause wear in the timing chain, and in the camshaft lobes and followers.
I'm sorry... low oil is a death sentence for an engine. It may have skipped the timing chain when the oil was low. This could explain the camshaft sensor code.
"Running good" is a subjective term. Once you are up to speed, you won't feel misfires in the engine. I suppose a possibility for misfires on 1,2, and 3 could be an intake plenum leak, but why would it start mysteriously at the same time the engine ran out of oil???
Think about this... it was running fine until it ran out of oil. It starts running poorly and starts setting many engine trouble codes. So it is logical to assume that the running out of oil incident had a negative effect on the engine. I would not recommend throwing any more parts at the engine until you see a mechanic.