do you know how i can check to see if i have an intake leak?

Intake gaskets can leak oil, coolant, and vacuum. What type of leak do you have.

i believe its air, the van idles very rough but run great past 15mph. I saw a missing bolt where I believe the intake connects to the head, its near plug number two. But i haven't had a chance to inspect further. Please help or do you think it might be the camshaft??? Any other ideas/suggestions?

While the engine is idling, spray carb cleaner along the intake, if it smooths out/speeds up, you found the leak.

thank you i will try it tommorrow and post back my results, thanks