Some smoke from the draft tube is normal... These trucks always have some blow by. It's only a concern when it becomes excessive. I.e. Blowing a loose oil cap off... However if it was as bad as I'm seeming to think, I would expect your dipstick would be getting pushed out when the oil cap was tightened down.
How's it running with the new bad injector? If it's running better do this for me, take oil cap off then just sit it back in but don't tighten it. Wrap the engine up to around 2000 rpm. Excessive blow by to worry about will blow the cap off, if it's still sitting there I wouldn't worry about it


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