Smoke On Startup and reving

My s10 4.3 has been blowing a bit of white\black smoke for the past few months and was just wondering what it could be. I never have to add any oil and the engine doesn't knock, but when i see the smoke, there is a rattling noise that goes along with it, around 1200rpms. This truck smells like a lawn mower. It sound like valve stem oil seals or piston rings. The engine only has 107,000 on it.

What color is the smoke?
Any sweet smell to it?
Does it use any coolant or have any engine miss when first started?
MT

It's not using coolent, and the exhaust smells exactly like a lawn mower. If I park this truck in the carport, it will stink the whole house up like gas, even if the truck is on for only a few seconds. The radiator is still full of bright green antifreeze, and the oil is still light brown like it should be, but smells like gas. The smoke almost looks gray when it comes out, and if I get on the gas to try to pass someone, it looks like a diesal smoking. I had the computer scanned, and it said bad egr valve and bad o2 sensor, so I replaced those, but the truck is still doing it, and I am completly clogging the cats every 2 months.

What year?
If gas in oil you have a engine running problem.
And will wipe out engine if not fixed.
Check engine for running rich and fuel pressure readings and fuel pressure leak down.
Get it on a engine capable scanner and watch and check all sensor readings.
Good luck
MT