I have a 93 civic with a H22 swap. I have a chipped p28. The car will idle just fine. But out of no where it will idle at 2500 rpm. Has anyone had this problem? Then it will throw a code 43 (fuel system code) and idle at 1500 without any problems. My diagnosis points to an iac or the thermal valve. We have changed the iac with others (used not new) and this still happens. So I'm thinking that the Thermal valve is the problem. We have installed three different iac's.