Hate beating a dead horse, poor guy. First area that I will always check is at the miserably designed connector that ties the ignition switch to the under dash harness, followed by the bulkhead connectors.

I just ordered up a replacement under dash harness for my Challenger as I have tired of dealing with this flakey ill conceived connector. Not the only reason, but the one that pushed me over the cliff,,,some 600 bucks minus current Year 1 discount of 25 percent.

The fusible link idea is another reasonable thought as posted above.

Does any other electrical function on your car,,,brake lite and dome lite are on same fuse.

We are assuming that your battery cables are securely tightened and clean at each end.