After inserting key and turning to start position, starter continues to crank after engine starts. You can turn ignition off and remove key and starter continues to crank. have replaced solenoid, ignition tumblers and starter. What could be sticking to cause starter to continue to crank?
When you say you have replaced the ignition tumblers, I am presuming you have replaced the electricial switch on the back of tumblers, so let's forget about that.
Seeing as you need to initiate this by turning the key, it can't be a short somewhere.
If the starter is indeed being powered at this point, the only thing left that could cause this is the starter relay in the fuse box.
Since you didn't replace the switch, then the switch is also possibly faulty. For simplicity I would first try swapping the starter relay in the fuse box for an identical one if there is one. If that doesn't fix it, then the next thing to change would be the ignition switch.