guys im new to this dodge neon.......so ok i bought this dodge neon rt 2001 167k miles........cars drove fine only issue was over heating finally came to the conclusion bad thermostat and we fixed that but now i was driving it home comming off the freeway i jus cruised it until the stop sign got to the stop sign shifted into first and it got real stiff and the car shook...... tried to drive and as i pushed the gas and let go of clutch the car shuddered again...when into 2nd and same thing the car shudddered as i shifted gears like sputtering the first few miles then stops until i shift again and it sputters again ...... the car never did this before i had it a week until this happpened.... what could it be?!?!?!? and ideas would help... thanks and its throwing these codes p1684 and p1685...how do i get those fixed?

 

Welcome to DF
Doesn't sound like a clutch, sounds more like a engine misfire.

 

P1684 is meaningless. P1685 is an "invalid SKIM key." You can start and drive your car though, so I'm not sure why that code is showing up.