There's your problem more than likely. The timing is controlled 2 ways. Where you set the static timing, and how much more the computer adds. The wire controlling the computer added timing has a device in it called a spout. When you pull the spout out, it disconnects the computer from the distributor allowing you to set the initial static timing. By setting it at 10 btdc with the spout in, your static timing is about 0 degrees btdc to 4 degrees atdc. That's why it's running so crappy - WAY retarded timing.
On Fox bodies the spout is a little device about 3" back from the dist. module on the dist. wiring harness. You'll see it - it has a little fuse-looking device that can be removed. If you remove it first, your timing is set now so far retarded that it probably won't start. So start the car; put the timing light on it and set the timing at about 20 degrees btdc; then remove the spout; now, use the light again, and set it at about 12-14 btdc (with the spout out); then plug the spout back in. The timing will jump up to around 20-24 when you do that. That cam is gonna want more than stock timing - I'd run as much as you can without detonation 14-16 if you can get away with it.
Try that and see if it helps.