I have a oil blow-by up flex hose to air cleaner snorkel and from filler cap. Truck is bucking when driving. Any advice would be appreciated.

 

Is there oil getting into the air filter? Is there oil accumulating in the carb or throttle body? Do you have TBI or a carb?

 

It is TBI and there was some oil in the air filter and throttle body.

 

I would say that you have a little too much blow-bye, and that is what is causing the oil to get all of the way up into the filter and then get sucked up into the TBI. Once it is there, it can get down and foul out plugs.
Next, check your plugs and see if any of them are burned up or so oily that it doesn't look like they are burning at all then change them out. Another thing that is really common with the older model 350's is the valve seals, they tend to go bad quicker than others.

If that is not your problem then it could be fuel, which incidently can also be determined by the plugs. So go online and find pictures of what good and burned and oily plugs look like and then pull yours and see if you have any problems.

If they all look good, let us know. And post pictures, there are some picture people on here! I could care less.