05 Mazda 3 Engine Mounts/Other Problems
 

I just started to have trouble with my Mazda 3 and need some help/advice.
Here's the issues:
the engine began to run a little rough and eventually started to die after I came to a stop. If I gave it some gas, it would stay running but if i didn't continue giving it gas, it would die. I took it to a Mazda dealer nearby and they diagnosed it as two valves had failed. They were replaced.
Next, the check engine light came on and has continued to come on since this was fixed. I took it in and the code P0507 came up. They suggested that the computer needed work, to be reset. This I have not had fixed.
The next issue is the common problem with the engine mounts. That will be fixed within the next few weeks as a DIY bc I'm not spending $300 to have the one replaced that is failing.

My question is, the code that continues to pop up p0507, has anyone seen this code on their 05 mazda 3?
My dealer suggested that I have the ETC replaced/worked on - im not car savy by any means and do not have my paper infront of me from the dealer at the moment but I know that is the engine trottle control.
What do you suggest I do with this code and do you have any suggestions for GOOD replacement mounts?