just got a brand new notor from mazda. its for an 06 at. wen car warms up idle pulses and often stalls. http://www.youtube.com/watch?v=7TIuZ...ature=youtu.be

 

It's a bit low and changes a bit slower than 'normal' for this, but... neutral switch is my guess.

If you push in the clutch and put it in gear at idle and it stops, then it's the neutral switch. The neutral switch will also throw a CEL after a couple drive cycles with it not reading right. Often referred to as "idle hunting".

Usual neutral switch malfunction issues include: incorrect re-connection of the neutral switch wiring at the transmission after the transmission is removed (needed to pull the engine), wire harness that includes it gets damage after getting pinched between the transmission and engine, wire damaged in the footwell near the clutch pedal (runs through one of the two clutch switches). Also possible that the neutral sensor itself is failing, though that's much less common.

 

its an automatic

 

Pretty much exactly what mine did at first with the replacement engine. It'd rev up a few times like yours is, then stall.

Mazda then did some sort of intake cleaning service, and it was fine after that. I'm not convinced the service did it though, it might just have taken more time and driving to either clean things out after the installation, or let the computer relearn things.\

Edit: my old thread: https://www.rx8club.com/series-i-trouble-shooting-95/replacement-engine-stalls-idle-218004/, "they cleaned not only the injectors, but also the throttle body, air intake system and intake valves."

 

id say neutral safety switch, but you don't have one.

Next I'd say vacuum leak, or VDI and the SSV vacuum lines are swapped. Thats really just a shot in the dark, I try to stay away from troubleshooting auto's. Good luck sir!