Earlier I posted that I had a bad vacuum leak in my '82 pickup. I noticed that the truck idles well when cold but then begins to growl and shake when it gets warm. It seems like it's blowing some steam out the exhaust too (only when warm). So I'm thinking that I've got a bad head gasket. However, it's not leaking too bad because there is no water in the oil. My question is this...could a leaking head gasket give me the symptoms of a bad vacuum leak too? I can't get it to idle unless the choke is almost fully shut, telling me that I'm getting too much air. How much does a decent head gasket cost and should I avoid buying it from certain places?