Once again I come to you guys for help regarding my 1995 isuzu pickup. 2.2 liter engine 4cyl. I checked all the other stuff and replaced the plugs, oxygen sensor, fuel filter. I had a guy look at it and here is where it gets weird. On the back of the block, there is this little cylinder type thing with three hoses coming out of it. Two of them go to a little disc type thing on the driver side of block. the other hose goes to manifold. the cylinder itself is not bolted down in anyway, just clipped into the frame. He took off one of the hoses and plugged the hole up on the cylinder and the truck started running like a champ. Put the hose back on and it started loping again. Any idea what this piece is? It measures approx. 2inches by 2 inches around and the hoses average in length 6-8 inches. About 1/4inch in diameter.