Help! 2005 Scion tC
 

I have a 2005 automatic tC. Recently, it has been cutting off (engine stops but radio/lights stay on) whenever the gear selector goes past neutral.

Example

Park to Reverse fine
Reverse to Park fine
Park to Drive cuts off
Reverse to Drive cuts off
Drive to Reverse or Park cuts off
But it stays on from D to 2 and L and back up until it hits neutral, then cuts off.


Whenever the car cuts off, i just start it in neutral, put it in drive and it's fine again.
I was thinking that it could be the neutral safety switch, but I'm not sure since I can start it in neutral and in park of course.
The car drives fine, idles fine, no slipping from the trans or anything like that. Just cuts off when the gear selector is passing neutral but always starts right back up.

I do have a CEL on but it's for emissions code P2420

I've been told I that its a dirty throttle body, or i should replace the throttle body, that its the throttle position sensor, that it's the IAC and that I just need a tune up :ponder:
Of course trial and error can be expensive but at this point I just want it fixed

Any ideas??

Sounds like the torque converter is locking up. Course that's the most expensive fix, I would start with the small things you mentioned first. The IAC is built into the throttle body. Clean the throttle body (doesn't hurt to do if you have a lot of miles anyway) and if you know anyone with a tC that's auto 1G, try and switch out the shifters and maybe the throttle body (our throttle bodies have some weird issues). I'm lucky to have someone with the same car as me, so I can swap parts back and forth to narrow problems down. I just can't figure out my own idle issue even with part swapping, so I may be the wrong person to ask =/