Heavy white smoke from exhaust

Hello,

This can be a fuel injector stuck open, I've had this same issue in the shop, fuel injector stuck open pouring white smoke out of the exhaust. What you can do, is unplug each injector one by one until it stops smoking. And this way you can identify the problem quickly and rule out the injectors if it doesn't stop smoking. Just don't break the injector clips.

Oil in the air filter box is caused by excessive carbon build up in the crankcase. You may want to try an oil additive to break up some if the deposits. When the oil passages get clogged up, too much pressure builds up and forces oil into the wrong areas.

A leaking injector can cause poor everything, the computer may be seeing too much fuel in the exhaust and cutting back on the amount but of fuel being delivered, this is called fuel trim. The computer can go positive with fuel trim numbers, ie adding fuel to the mixture, or the opposite negative numbers, reducing fuel.