series of events, three months ago my key would not turn at all, after some one hours worth of jiggling it finally turned and started the engine, got home tried spare key never used worked fine. two month ago the car just shut off while driving. had it towed to shop and after 800 dollars said timing belt problems. today the car started jerking, and then just shut down again. all the accessories worked and key turned to start the car. started moving again and got the same jerking sensation and the car again shut down. this happened three times before I could get it back home. starts up fine but after a few seconds it repeated the same symptoms. I have been told today that it could be the key lock cylinder, that is an easy job to replace, any ideas as to whether a bad key lock cylinder could be the cause, or something more serious?