Hello all. New guy here with an 05 Neon SXT. Had it for about a year now and just trying to figure the car out. I also have the bad vibrating/ idle but mostly when it's in gear. My RPMs drop n it feels like it might stall but never does. I've replaced just about every sensor with the exception of the trans. range sensor! I have found no vacuum leaks either. I have a long list of new parts. Also, what's with the drop in RPMs after about 60mph? Almost feels like the car has a governor or something. I love the thing and have put a lot of time n money into it....

 

The RPM's drop while it is in gear and you are...stopped or driving? The drop in RPM's after 60MPH sounds like it is going into overdrive? It shifts at different times depending on how you are driving, so it's hard to say it is a problem over the internet. Does the car just not want to go or something after it shifts?

 

Hello again...Starting to "learn" how to drive this car....! I am beginning to see now that it is a bit sensitive maybe (?) In any case the drop in RPMs occurs after the car warms up and in gear. If I shift to neutral and back to drive the RPMs go back up or if I switch the AC on then off....I think I also might have to change the motor/ trans. mounts again. I bought after market ones last year but I just might have to go with OEM ones. This thing vibrates like a truck!

 

I have the exact issue you are describing on my 05 SXT. I am taking it into the shop this Wednesday to get it checked out. I have a feeling it may be a busted motor mount. It seemed to get worse over the last few months. I replaced the upper and lower motor mounts and that did not fix it. Tuned it up with new filter, plugs and wires, completely removed the throttle body and cleaned it as well as the MAF sensor...no luck. I hope the shop can fix it, it's horrible.