1997 Chevy Cavalier pin/rod issue maybe?

Engine Mechanical problem
1997 Chevy Cavalier 4 cyl Two Wheel Drive Manual 150k miles

bare with me, im new at all this. I have a 97 chevy cav, 2.2l stick shift. The clutch is sticky but thats not the biggest issue. When I first bought it, it was ok. Then a few days later it started sputtering as soon as it hit 4th gear and stalled. It started right back up but refused to go back into 4th without a repeat performance. I took it to the mechanic who couldnt find anything. On the way home, every light in my dash turned on and it started stalling again. I got it almost home before it stalled at a light and refused to start again ever since. While it was driving, there was a rattling sound coming from in the engine. The mechanic said it was external but others have told me otherwise. Ive heard it could have "thrown a pin/rod" but I dont know what either means, as I said, im new at this. Im hoping someone can tell me what happened.