Even if you have to replace the connector, its a five dollar part and 2 bolts, if your comfortable tightening it, replacing it isn’t much more. Hopefully tightening it gets it.

Make sure your negative actually has good contact. For a time the jumper then goes from the inside of my fender to battery was bad and my truck would randomly die and wiggling that would get it to start again until I replaced the wire end. That said yiu probably needto replace the ends.