No top end power, need help

So I just messed with the timing, tried 15, 20 ,25. Drove it and nk notible improvements. Started getting some pinging at 20/25. Currently set to 15. I don't have a tach so can't test at 3000. As i retarded the timming the rpm kept climbing, all the way to about 25 or so
As far as fuel goes. Sometimes the fuel filter emlties after sitting over night. And it was a used car BTW.