Car

You have an oil leak somewhere that is burning off. There's several places oil can leak from, so you'll have to find it. As long as it's not a fast leak (and your oil level remains topped off) you won't have to worry much.

As for your power loss, when was your last tune up? If it's been too long, begin there. After, if you still have low power, make sure the ignition is producing a strong spark and there's no misfires. Next make sure the fuel pressure is good and the filter good. Check injector flow. Lastly, check that you have good compression on all cylinders.