Hello all, my truck is having a few issues. The other day when I started it it almost died in traffic, and the engine was idling very rough and I had to apply gas to keep it going. I changed the plugs cause some simpletons at autozone told me that was probably my problem, but when I changed my plugs the engine would die if I didn't keep my foot on the gas. Now about two days later the truck has been running fine.

Now I have noticed one issue which is a fairly large hose(like 1/2-3/4" diameter) leading from the exhaust manifold to a vacuum diaphragm and then from the diaphragm to the bottom side of the air cleaner on top of the carb.
Now if you open up the air cleaner and hold your thumb over the hole through which this hose leads you can hear a crazy gurgling sound, and its even louder with your thumb removed. I have no idea what this sound is but its coming out of this hose, and I know that the sound can change in intensity, when it gets bad my truck dies.
(and I realized this hose might be the one which sends back unburned exhaust gasses back through the engine to be reburned.)
Any insight into this issue is very much appreciated.