I have recently swapped out a blown 360 in my 95 dodge ram 2500 for a 318 in good working order. The 318 is out of a 97 1500. It ran well at first, but now it is having idle problems. I am running the 318 off the old ECU from the 360. Is that causing the problem? I am getting a loud hiss from the IAC. When After it warms up the idle drops to below 500 rpm momentarily then kicks back up to 1500 and repeats. I have tried adjusting the minimum air to the throttle body with the result being idle at 3000 rpm! I have replaced the IAC, PCV, breather element, and throttle body gasket. Any input would be greatly appreciated!