Dissapointing performance

I did a test and backed timing to 15 degrees at idle (from 20). Car started to idle more poorly, but it accelerates better in lower rpm and started to make burnouts! Looks like I need to recurve my distributor and possibly add some vacuum advance to make it run better in part thorttle. Now car doesnt have vacuum advance at all. It gets full mechanical advance in at about 2000 rpm.