Any ideas why my fuel pressure would now be higher after I switched out the stock IAT in favor for a fast reacting one? The fuel pressure is higher at idle and low rpm's while still in vacuum.

 

my guess is vacuum leak!!

 

replacing the IAT will NOT affect your fuel pressure. They are two different system meant to be used differently.

However, when you do replace that IAT sensor, you couldve knocked off OR ripped the vacuum hoses to the fuel pressure regulator causing this higher fuel pressure.

Check that and you might find the problem.

-AzEKnightz

 

I'm pulling low vacuum at idle as well. Will be investigating it tomorrow. Thanks for the reply.

 

found the low vacuum issue, low compression in rear housing.