I have a '97 4runner with 135,000 miles.
When I put it into Park SOMETIMES the ignition switch refuses to turn all the way off, so that I can take the key out. I have replaced the switch and solenoid in the shift lever, figuring it was worn out.
That hasn't solved the problem. It is totally unpredictable. Sometimes just driving it a few feet or a few miles seems to allow it to release the key. What else could be causing the problem?

 

try replacing the ignition switch.

 

is an automatic? if so your shift linkage may be a little out of adjustment.you may have to adjust it.