5.3 Tuning Issue

I have a 5.3 Vortech in a 95 Sierra that I have just installed but I am having a tuning issue. I run EFI Live and I have had to put my VE table numbers up to around 130 at idle to get it to idle right, even then my Wide Band says im running 18-19:1 at start-up and then it slowly comes down to 14-15:1
Does anyone have any ideas???
Also... For whatever reason at start-up, I get a really clean start-up and then as the idle comes down it starts to hesitate and becomes harder to hold an idle, then I can hear the IAC motor begine to open up (probably 100%) as its sucking huge amounts of air through the TB. Sometimes it will just die and others it makes it past this point and the idle cleans back up and the IAC begines to close back up. But every couple of combustion cycles the idle will drop to 300 as it feels like it had a miss and then resumes to 650.
Any help would be great!!