I have found that the Toyota electronic ignitions severly **** the timing while cranking when they start failing.

When I come across a Toyota that starts very hard, but runs fine, I try advancing the timing while cranking. If it starts fine while the dist is advanced, but then runs lousy because the timing is so far advanced, it's time for a new dist.

Although it's cheaper to just replace the ignitor, I found out the hard way to replace the entire dist- dealer won't warranty individual dist parts, just complete dist.