I am thinking if your fuel pump is still from when they installed it in 1990 (more than likely the year built like mine was) then it may be on its way out because with half of tank it dies out.
you may have also gotten a bad tank of gas.
how did the gas smell when you replaced the filter? how dirty were the spark plugs when you replaced them?
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if you can only race me in a straight line then whats the point 
...91 SMF SCCA
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by http://www.flickr.com/people/8341770@N07/, on Flickr
I see people out there spending money on the car to improve it … If you spend half that effort just working on your driving skills, making you and the car work together as a team, then you’ll go faster – period. To make the car go a second faster on the track takes a lot more energy and money than making yourself drive it one second faster.
– the late Tom Thrash SCCA Solo E Production