2000 dodge ram idle rough has a tick only under a load

I have a 2000 dodge ram with a 5.2l auto 4x4. It runs rough like the idle bounces up and down and also stalls itself out when in park or in neutral and when you shift into gear it sometimes stalls out when you first shift or slow down won't stay running and when in park or neutral you can rev it up with no issue and no noises from the motor but once put into gear and gets up to about 1600 rpm's it makes like a scrapping or ticking noise I used a scope to listen to the engine and no noise but you can here a faint tick from the intake manifold and more when moving I only know this because I stood on the front bumper and listened to it while we drove down the road a bit. please tell me what is going on. It only happens under a load.