PLEASE HELP....

What color is the smoke and what does the plug look like wet dry white black be as descriptive as possible.It might be a injector stuck open some or o2 sensor in that side of the exhaust.Could be the valve stem seal too depending on what the plugs look like and color of the smoke.Maybe a egr valve stuck open many of things come to mind.Be more descriptive.

do a compression test. does it puff a little cloud of whitish blue smoke on startup. if so then the valve guides are worn. how many miles on it, i would go ahead and get the heads rebuilt and shaved. it does not cost but 100 dollars here.