Hi guys. I'm looking for somewhere to search before I begin tear down. The history first. Got a '94 K-2500 GMC truck. 350 engine, target motor, 8,000 miles. I picked the motor up used from a wreck for $350.00, so, basically, I stole it. Bolt all the goodies on, pollution controls are functioning, and the engine smogged ok. It burns about a quart of oil every 800 miles. I stopped driving it until we get this problem handled. Problem being....At an idle, like at lights, this engine begins puffing smoke, then if you sit long enough, looks as though it foggs mosquitoes until it clears out. My first thought was try the easy stuff first, and that is why the pollution garbage was checked out first... I read a tech bulletin a while back where GM had troubles with intake manifold gaskets, so the vacuum would suck oil right out of the valley and do what this motor is doing. The other issue could be valve guide seals. I have not yet pulled compression, which I am assuming will be fine, and will look for plug discoloration when I do. So, given this history, if this was your engine, where would you begin looking to solve this problem?