I bought my 86 300SDL about 10k miles ago. When I bought it I replaced the primary and secondary fuel filter. I drove it 2k miles home approx. On the way home I replaced the filters again since it was way too sluggish going up the Rocky Mountains. Again, a few months ago it got way to sluggish so I replaced them and again the car ran much better. After just about 3 months (driving 60 miles per day roundtrip to work) I had to replace them again.

I am assuming that I should not need to replace them this frequently. My guess is that I need to check the filter inside the tank for gunk/algae and clean out the tank if necessary. Does this sound right?