Car Idles low and sometimes stalls
 

Hi! I have a Automatic 98 Honda Civic and lately I've been having this problem where my car idles down to about 300 rmp when i stop. I'm worried because when I put my foot on the gas to go it stalls or vibrates weird like it's about to cut off.:confused: My brother says it may be my idle air control valve, but I'd like to get other suggestions without paying $64 for a diagnostics test.

Thanks!;)