Just installed the new main relay. Haven't started the car in about a month. I had put some fuel stabilizer in it a month ago. Those are the only two things I've done. I let the car run for a little while. 10 minutes, roughly. It's still revving at 4500RPM. It's really loud. I'm afraid to put it in gear. Could the relay be causing this?

I bought it used, but refurbished. It's the OEM model.

 

Okay, I kept thinking I was hearing the fuel pump running, even with the car off. So I took out the main relay. STILL thought I was hearing the fuel pump. Disconnected the battery.

STILL THINK I'M HEARING THE FUEL PUMP! Weird!

 

Fixed it. WOOHOO!

For anyone else who my have this problem and stumbles across this thread, try pulling the ECU fuse for about 30 seconds. Worked for me.