The car is running very rich. I've done a full throttle body rebuild,and put new injectors in,and there's been no improvement on it running rich. I always thought that it was done by the computer automatically. Is it done like that,or some other way?

 

Yes, air/fuel is controlled by the computer.
Is your check engine light on? Have you checked for any stored codes?
A bad O2 sensor is a common cause for a fuel injected car to run rich.
A bad fuel pressure regulator can also be an issue.
I'll have to defer to the more knowledgeable for other culprits.

 

The fuel pressure regulator is on the throttle body correct? If so,I replaced the diaphragm for it during the rebuild.

I can't remember if there's a recent code or not. In the past I had an IAT code,but I think I solved that by plugging the harness into it. Where's the O2 sensor located?

 

O2 sensors are on the exhaust manifolds/headers depending on your setup. Quick and pretty cheap to replace.

 

You don't "adjust" the mixture, except with a tune.

I'd suggest just replacing the O2 sensor (driver's side exh manifold) and the coolant temp sensor (front of intake, 1 yellow & 1 black wire). They're both CHEEEEEEEEEP and EEEEEEEEEEEEEEEEEEZY. While just randomly replacing parts for no reason isn't always "the best" way to deal with such things, sometimes it is; it's more expense and/or more trouble to handle the situation any other way.

 

Ok thanks