I'm really buggin' now, still running 17's I noticed it dropped about .2 every run, so that has to be the weather factor, but I'm still not quite topping out where I should. I'm pulling consistant 2.6 60's but my first(and still best unfortunately) run had a 2.6 and I still ran a 16.67 what else could be causing this performace lag? I had about a half tank of gas, vs a little under a quarter in my best run. Also could it be my plugs? I'm not sure when they were changed last. Any help would be greatly appreciated.

1995 RS
new engine, I think I'm just going to leave it stock now.