I recently replace the throotle body, egr, maf, and pipe on my coupe. when I was changing over the throttle body, and installed a new IAC valve I noticed the small plate in between. The alan screws were all the way closed. I opened them a little. Now when I started the car it Idles at about 2000 rpm. I know I need to adjust thes screws back, and be sure the TPS is set right. My question is exactly what purpose do they serve?, and how do I know where they should be?