I would concentrate on not getting worked up on the little things. I found the thread you were talking about. Spouting qualifications does not make you right or wrong. MAKG may not be the most subtle person here, but he does know his stuff.
Your first reply in the aforementioned thread did little to help the guy and did nothing for a newbie in terms of finding the root cause of the problem. You went into more detail in your second post about WHAT could cause the problem, which gives the OP a place to start looking, whether or not it turns out to be correct, but you did so in a confrontational tone directed at another board member. You probably scared the OP away.
The only way you can take offense to someone disagreeing with you, while listing out his own thoughts, is if you really do know it all. And those who think they know it all greatly annoy those of us who do.

Treat a diagnostic thread more like a differential diagnosis and keep the OP involved until the problem is fixed...or he sells the truck. It's no different than how the service manuals walk you through a set of logical steps to eliminate all incorrect assumptions about the problem.