Chances are if it is the Ignition, you can junkyard the parts cheaply. These rarely from what I know of have issues. If you need to, a locksmith can rekey the salvaged one to your key. Nomally costs about 30 dollars.
Fords are notorious for having an issue simular to this and the easiest fix it to chip in a hole on the column for access with a needle nose to manually pull a small bar in the top of the column. Generally for this fix to be required you will notice that you gotta move the steering wheel back and forth until it finds the right spot to make contact. This was also most noted in early to mid 90's trucks.
I have noted on some GM vans and Trucks, you need to actually fiddle with the gear shifter, moving it back and forth because it seems that the gear indicator is not pointing to the propper spot. Because of this, it looks like you are dead on, but the shifter is just a little bit off. Meanning you need to find a sweet spot before turn the key or start it.
I also do faintly remember some of them do have a soloniod I think on the tranny that can go bad causing a simular issue but not sure on exact year range and / or model. It has been a while and I cant remember who told me about it.