Almost impossible to troubleshoot aftermarket and modified wiring.
Autometer: I believe these are what is called a bridge type gauge, but the important thing is I believe the gauge MUST be grounded, or have a ground terminal that is so grounded. When you unhook the sender, what does the gauge do? You ARE? using the correct sender for the gauge. MUST be the correct Autometer sender and not Mopar or something else
Fans: These a kit, or junk yard ones you've pieced together? You have a link or diagram how you wired them? Unhook one motor at a time and try it. 30A may not be enough for both motors. You have specs? on the motors? Who made 'em, model? What are they rated for amperage?