So since im not running a IAC valve I need to try to have as stable as a idle I can. Before the external regulator, Megasquirt was seeing 13v-13.6. So, I installed my regulator sanded paint down and grounded it on my firewall. I started the car and megasquirt displayed 14.2v-14.6v, I was ecstatic but then maybe a hour after of messing with my idle/tunning. I relized my voltage slowly started declining back to what it was. Anyone have a similar experience or know my problem?

The external regulators are fairly temperature sensitive. As they heat up, the voltage drops. Depending on where you have it mounted it will be affected by heat soak.

Dave why are you a genius? So I’m 100% sure that you are correct and that this is my problem. I work at 4am here in MASS where the temperature was about 15* degrees. At startup megasquirt displayed 14.6v and after my 25minute ride to work voltage was just about 14.2.
Once I was out of work temps were up 25*degrees, initial startup was 14.6v and by the time I got home voltage was down to 13.6-13.8v. So Dave did you run an external vr? if so where? Or any ideas for placement?