I drove my brother in law's 1997 Yukon with a 5.7 Vortec last week and noticed a couple things that aren't quite right. I know, not a Chevy... anyway, I was wondering if anyone could give me an idea what the following things might indicate and where to troubleshoot:

1. When the car is sitting in park, idling, there is a clanking noise above the gas tank. I hear it best by looking at the tank from the driver's side rear wheel well. I at first thought it must be something exhaust related, but I climbed clear under and it isn't. I think it has to be in, above or next to the gas tank. Any ideas what would make noises in there? It isn't the normal fuel pump whine... it's more of a clattering noise.

2. When I was going up good-sized hills with cruise control on, the speed would go down significantly. If I put my foot on the gas, it had plenty of power... I am guessing I should be looking for a vacuum leak, but wonder if anyone has any other ideas.

Thanks!

--Matthew