I replaced my filter on my 86.5 and it obviously had some bad rust in it. My fuel pump died the next day. So i take my tank off and it is very rusty and my pump was all gunked up. So i cleaned it out many times with water, then gas, then let it dry for several days. New fuel pump (ebay - $20
) and put it all back together. Put a FULL TANK of 93 octane good quality fuel in and a can of sea foam (or stablizer or whatever to clean that stuff out). I noticed a difference in power with the new filter and new pump. So when your almost out of gas you could take your tank off and take a look (easier said then done). Or there is an inspection plate in the trunk where you can take the fuel sender unit out. But I would say that you have a rusty tank that needs cleaning, a fuel pump on its last legs, and some gunk in the system - because thats what I had
. Good Luck!