should my pcv always be open? if i pull pcv out oh valve cover should there be a strong vacumn or any at all? my truck is idleing weird bounces up in down between 600-700 rpm

 

Remove the pcv valve and shake it. If it rattles it's okay.

 

To answer your question, Yes, there is always vacuum at the pcv valve. An old guys memory and knowledge. Back in the late 50's or early 60's, crankcases were vented to the atmosphere. Not nice! So along came the pcv system. The intake vacuum was/is used to take the crankcase pressures (air) and pull it back into the intake and reburn it. At all throttle positions except full or WOT position there is vacuum. At WOT, vacuum and crankcase pressures are for simplicity of conversation, equal thus the check valve to prevent oil particulates (love that word) from being picked up and reburned. Hope this helps. In your case, as Sean says, if the valve rattles its good to go. Doubt very much if its the cause of your surging idle.

 

EGR valve maybe?

 

ok thanx im gonna change filter just incase because i think it may be cracked...

 

egr is removed and plated off been turned off in program.. i think its probably the filter i installed.. when i remove pcv and caver it with my finger it idles fine so i think there is a crack in filter letting vacumn pull more air...