My blazer was acting crazy almost 2 yrs ago now

When I put the key in, every now and then it just did not turn off, take the key out & try again, it started up no problem. Now I made hubby drive it and it never happened to him, grrr. Then when it did start it would rev up for no reason, even driving down the road it would make that odd revving up noise for no reason. Hubby thought I was going nuts. It never did it when he was driving, so he had me drive and he rode, nope still never did it. Yet for me & the kids alone in the car it did it a lot. Well he had to go to Korea for a year, he after about 9 months he came home to visit and that stinky car FINALLY did it for him, of course now the car had to go to the shop, lol. Turns out the thing you put the key into, that cylinder thing was acting up. They said it is rather common, and to not put anything but that key on the key ring, to prevent it. Cost over 300 to replace that and key it to match my car key. Better then having to make keys and have 1 for the doors & 1 for starting it.
Hubby looked it up online and asked several car people friends. We took it to mechanics that would do a free look, transmission specialists, firestone, all sorts of people. Nope they couldn’t figure it out. GRR.
But we did finally get it fixed and it hasn’t been acting like that since.