Q: My car turns off while im driving and sometimes while idle. Today I put it in 3rd gear and it turned off instantly.

My car turns off while driving.Mostly when I put it into a gear . While i'm driving i'll go into a gear fine , then all of a suden the car will start jerking and turn off, or before it turns off ill hurry and put it into another gear and itll stay on. When its just running , it'll run and then after a while the engine will sound like its struggling to stay on. It makes a put put noise and then goes back to running , but sometimes it'll cut off. I already know it's not my altenator because my car runs without the battery being connected if previously started. I know that its not my electrical system because my lights and radio and everything else still work fine. My brake cylinder needs to be replace because its leakin brake fluid but I dont think that has any coordnation to my problem , but then again im no mechanic.

My car has 250000 miles.
My car has a manual transmission.