Hello everyone, Z newbie here again requesting help. I got my Z running again although it was running very, very poorly. I bought it back in December and it had been sitting since '03. The previous owner said there was old gas in the tank and so I drained it, filled it back up and after changing everything from the plugs to all the 'pumps' in the engine bay, I ran it for a while. I recently changed my fuel filter because my Z was not running, seeming to be starved of fuel (delayed response when stepping on gas, 'choking' and jerking when I floor it.) Anywho... I was very surprised (not in a good way) when I removed the fuel filter I put back in December, when I noticed it weighed about a quarter pound. Inside there is all this build up of gunk or something. It is brown and it almost looks like modeling clay, although it is soft like a paste, probably because it was mixing with the fuel. I know I need to clean out my tank, but I was wonder if: 1. Anyone knows what this gunk side is? and 2. If it would be an easy DIY to clean out the tank? Thanks in advance for all of your help!