I have a 2002 Neon. With 115,000 miles on it. I've taken care of her, or at least i thought i have. lol. Yesterday, My son and I were on our way to town and all of a sudden my check engine light came on and it seemed like the motor was jumping. It seemed to almost pull inself sometimes and then others not want to go at all. Now to start it up, it sounds like a sputter, or jumping and idles really fast. Not knocking (i know what a blown motor sounds like). I got it to pull up a code and the code says P1299, I've searched and I've found the code means vaccum leak. Well I have checked (i think) the Break Booster Hose and the Hose to the carbiorator(?). Still does the exact same thing. Any ideas on what my problem could be? Any help would be greatly appreciated!!!

 

I'm assuming you have already stood with the hood open and listened to the engine run to see if there is a hissing sound?

You can use a piece of tubing held to one ear and manipulate the other end of the tubing as a stethoscope to track the source of sounds.

No other symptoms like in increased effort in braking or abnormal shifting?

 

Trace the vacuum lines throughout the engine. Other common places to have problems are EGR, evap, and purge. Sounds like the computer is trying to compensate (thus the rapid rpm changes) so your idle is probably okay.