This... and once you've tired of guessing, get a fuel pressure gauge and an air/fuel ratio meter with data-log capability and an rpm converter.i really wish people would stop spreading this false info, it is not physically possible for the distributor to be "off a tooth", as long as theres range for adjustment to the setting you want, and your timing light is showing the right value, you're there (assuming no error on the balancer or pointer, which CAN happen). just make sure when you set it, that the pip is out. 10 is stock base, 12-14 usually works well for a BASE setting, once the pip is back in it will add about 10 degrees or so advance at idle (exact number escapes me, but you will see it).
like mentioned above, check for vac leaks, compression check, even hook your timing light up to each plug wire and make sure theyre firing (ive had a plug wire or two burn by accident with the gt40ps and bbk shortys i run). basically, just run a "stupid check" on everything. check plug gaps, fuel pressure, etc. run the codes, and post up what you get. get what you have running right first, and then you worry about changing cams, rockers, etc. what you have should be mid to low 13's if you can drive it and get it to hook, mph's should be around 100 give or take
Use these to determine why it's running poorly across the ENTIRE rpm range. The alternative is to get some dyno time in order to get the same data.