Very odd idle, need help!

So I recently replaced my airfilter, PVC valve, and breather filter because I was getting oil into my airfilter housing causing rot of the filter and the truck to run rough. Changed the oil and it ran better for about a week. Just recently ive noticed that as it heats up the idle becomes worse and worse (almost completely dying but never will). Power goes down and cruising at about 40-55 is almost impossible without an occasional bucking from the motor. Took off the top of the airfilter housing and found that the new airfilter was already starting to rust around the screen and collect oil. Ran some carb cleaner on the linkage and thru the carb and it still runs rough. Right now (I know this is stupid) I;m driving the truck with out the top of the filter housing on and it runs great! Even if I put the top back on without the airfilter it still runs like crud. Any suggestions? I was thinking piston rings are shot and it cant create enough vacuum when the housing is together? Thanks in advance!

I doubt that's it......sounds like you have a carb problem or a vacuum hose disconnected. When it is warmed all the way up, is the choke plate at the top of the carb all the way opened? It should be in a vertical position if it is opened as it should be when the engine is at normal operating temp.

In a quick tip,new plugs,wires,(I use accel 8mm wires cut and crimp to fit) buy a v8 set for two sets.Next clean your egr valve,and check your charge air filters on the air cleaner(has 3 rubber hoses on the front) remove that and swap out those nasty filters with some new ones.You can use any filter air breather and cut to size.Next how is your pre convertor below your exh manifold.It has screens inside that big jar size canister that might be blocked up.And for the carb just cleaning the linkage is good,but a solid rebuild especially the sensors and float and orings inside replaced.Replacing your vacumm lines helps old cracked,brittle lines lose vacumm.No more stuff just some simple tips.Hope this helps