Joe,
These things are really simple to get going but they have some limitations when you push them.
The inductor needs to be sized reasonably closely to the calculated correct value otherwise the switch current gets to its maximum value too soon.
There is an excellent Application note from Onsemi/motorola "M34063A-D".
Just go through this AN and see if you can identify your problem.
I have done some of the things you seem to be trying to do, and generally I have to fiddle with the timing capacitor.
hope this helps.